STRATEGIES FOR MANAGING NATURAL SOUNDS FOR HUMAN

The Pennsylvania State University

The Graduate School

College of Health and Human Development

STRATEGIES FOR MANAGING NATURAL SOUNDS FOR HUMAN EXPERIENCE

AND ECOSYSTEM SERVICES

A Dissertation in

Recreation, Park and Tourism Management & Human Dimensions of Natural Resources and the

Environment

by

Lauren Abbott Ferguson

2018 Lauren Abbott Ferguson

Submitted in Partial Fulfillment

of the Requirements

for the Degree of

Doctor of Philosophy

August 2018

The dissertation of Lauren Abbott Ferguson was reviewed and approved* by the following:

Peter Newman

Professor and Head of Department of Recreation, Park and Tourism Management

Dissertation Co-Advisor

Co-Chair of Committee

B. Derrick Taff

Assistant Professor of Recreation, Park and Tourism Management

Dissertation Co-Advisor

Co-Chair of Committee

Andrew Mowen

Associate Professor of Recreation, Park and Tourism Management

Justine Blandford

Assistant Professor of Geography

*Signatures are on file in the Graduate School

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ABSTRACT

A large body of evidence suggests that there are benefits from natural sound exposure to

human wellbeing. Conversely, man-made noise, from transportation and urbanization, has

damaging effects on overall health measures. Large cities and urban areas are expected to be

highly impacted by elevated levels of noise, however National Parks, places where one would

expect to find quiet, are also at risk for noise pollution. Park managers are mandated to protect

natural sounds for the benefits to human experience. The purpose of this dissertation is to explore

methods that aim to better understand the impacts of noise on human experiences in National

Parks. Data for these studies were collected at two different National Park Service (NPS) sites:

Muir Woods National Monument, and Denali National Park and Preserve. In the first chapter of

this dissertation, the state of soundscapes research is introduced. Chapters 2 through 4 were

written as stand-alone manuscripts that present and discuss study findings. Chapter 5 summarizes

the combined results of the three dissertation studies.

Chapter 2 utilized spatial modeling data that predicted noise level across the United

States to measure factors that influence visitor perceptions of soundscapes at Muir Woods

National Monument. Study findings suggest that the combined effects of noise sensitivity, the

ability to hear natural sounds, and the estimated average sound level of home zip code impact

soundscape perceptions. A linear relationship shows that the louder predicted sound levels of

one’s zip code boundary, the less pleasant the soundscape was perceived.

Chapter 3 used a collection of varying audio clips to determine thresholds for propeller

aircraft noise in Denali National Park and Preserve. In this study, an innovative method for

measuring human response to noise was tested. Multiple regression models were used to predict

visitor thresholds related to aircraft sound levels, as well as, the number of flights tolerated per

hour and per day.

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Chapter 4 examined visitor preferences for soundscape management along the hiking

trails at Muir Woods National Monument. An experimental design was used to test differences in

preference between respondents who viewed management signs along the trail and a control

group (without signs). Results showed that visitors prefer to see signs along the trail, asking

visitors to maintain quiet. Also, visitors exposed to signs during their time in the park, had a

significantly higher preference for management signs than the control group.

Chapter 5 discusses overall findings. Results from this dissertation suggest several

important findings related to measuring park soundscape experiences. (1) Visitors come to parks

with individual norms, beliefs, etc., and now we know that their exposure to sound at home can

impact their perceptions of the park soundscape. (2) A randomized suite of varying sound levels

is effective in determining thresholds for noise. And (3) Visitors generally prefer indirect forms

of soundscape management. Together these findings suggest the high level of regard that visitor’s

place on protecting natural sound conditions. Ultimately, experiencing the benefits of natural

sound are valuable to the national park experience. Together park managers and social scientists

should continue to understand the human experience in relation to soundscapes so that future

generations can enjoy the benefits of natural sound.

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TABLE OF CONTENTS

List of Figures .......................................................................................................................... vii

List of Tables ........................................................................................................................... viii

Acknowledgements .................................................................................................................. ix

Chapter 1 Introduction ............................................................................................................. 1

What is a soundscape? ..................................................................................................... 3 The Importance of Sounds ............................................................................................... 4 Natural Sound and Resource Protection .......................................................................... 6 Indicators and Standards of Soundscape Quality ............................................................. 8 Natural Sound as an Ecosystem Service .......................................................................... 9 Methods Used in Natural Resource Management ............................................................ 12 Summary .......................................................................................................................... 16 Dissertation Purpose and Structure .................................................................................. 17 References ........................................................................................................................ 18

Chapter 2 Impacts on Visitor Perceptions of Soundscapes in Muir Woods National

Monument ........................................................................................................................ 33

Introduction ...................................................................................................................... 34 Methods ............................................................................................................................ 41

Analysis of the perception of the soundscape .......................................................... 48 Results .............................................................................................................................. 49 Discussion ........................................................................................................................ 52 Conclusion ....................................................................................................................... 57 References ........................................................................................................................ 58

Chapter 3 Aircraft Sound Management in Denali National Park and Preserve ....................... 71

Introduction ...................................................................................................................... 72 Literature Review ............................................................................................................. 73

Protecting Natural Sound in Parks ........................................................................... 73 Dose Response Methods .......................................................................................... 75 Indicators and Thresholds for Soundscape Quality .................................................. 77 Study Purpose ........................................................................................................... 80

Methods ............................................................................................................................ 80 Survey Location ....................................................................................................... 80 Audio Clip Dose Response Survey .......................................................................... 82

Results .............................................................................................................................. 87 Discussion ........................................................................................................................ 92

Management implications ........................................................................................ 95 Conclusion ....................................................................................................................... 96 References ........................................................................................................................ 97

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Chapter 4 Visitor Preferences for Soundscape Management in Muir Woods National

Monument ........................................................................................................................ 107

Introduction ...................................................................................................................... 108 Soundscape Management ......................................................................................... 109 Management Strategies ............................................................................................ 110 Study Justification .................................................................................................... 114 Study Site ................................................................................................................. 115 Experimental Design ................................................................................................ 116 Survey Administration ............................................................................................. 117 Choice Experiment Design ....................................................................................... 118 Model Analysis ........................................................................................................ 120

Results .............................................................................................................................. 121 Sample Profile .......................................................................................................... 121 Stated Choice Model ................................................................................................ 122 Preferences for Park Closure .................................................................................... 126

Discussion ........................................................................................................................ 127 RQ1: What tradeoffs are visitors willing to make in order to hear natural sounds

in Muir Woods National Monument? ............................................................... 127 RQ2: Are preferences different for visitors in the treatment group (signs present

asking visitors to maintain quiet) vs. the control group (all signs are

covered)? .......................................................................................................... 128 Management Implications ........................................................................................ 129

Conclusion ....................................................................................................................... 131 References ........................................................................................................................ 132

Chapter 5 Conclusion and Implications ................................................................................... 144

Summary of Findings and Implications ........................................................................... 144 Implications ...................................................................................................................... 146

Home Sound Level Influences Soundscape Perception ........................................... 147 Assessing Large Variety of Sound Levels Improves Validity of Soundscape

Thresholds ........................................................................................................ 147 Park Visitors Prefer Soundscape Management ........................................................ 148

Conclusion ....................................................................................................................... 148 Appendix A Chapter’s 2 &4 Survey Instrument ............................................................. 150 Appendix B Chapter 3 Survey Instrument ...................................................................... 166

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LIST OF FIGURES

Figure 2-1 Summary of Soundscape Elements that are comprised of sounds that are

natural (geophony), flora and fauna (biophony) and/or human-made (anthrophony) ..... 36

Figure 2-2. Estimation of sound levels and common sounds (adapted from NPS, 2008) ....... 37

Figure 2-3. The positive and negative effects natural and anthropogenic sound can have

on the wellbeing of humans. ............................................................................................ 37

Figure 2-4. Muir Woods National Monument (MUWO), the study area, is located X km

north of San Francisco, California ................................................................................... 42

Figure 2-5. Estimated soundscapes in MUWO ........................................................................ 48

Figure 2-6. Predicted daytime sound level and distribution of visitors’ home sound level

exposure ........................................................................................................................... 50

Figure 2-7. Distribution of sound level exposure .................................................................... 50

Figure 3-1. Summary of survey response for acceptability for varying sound levels .............. 85

Figure 3-2. Predicted relationship between visitor acceptability and aircraft noise level

using survey data collected at all sites (MSLC, HL, HO, and MSLC). ........................... 89

Figure 3-3. Predicted acceptability models by number of overflights (3, 9, 15, or 30

minutes per hour). Solid lines represent the predicted relationship between

acceptability and sound level ........................................................................................... 89

Figure 3-4. Predicted acceptability models by number of overflights (1, 10, 25, 50, or 100

times per day). Solid lines represent the predicted relationship between acceptability

and noise level. ................................................................................................................. 90

Figure 3-5. Predicted relationship between visitor interpretation (pleasing to annoying)

and aircraft noise level using survey data collected at all sites (MSLC, HL, HO, and

MSLC). ............................................................................................................................ 90

Figure 4-1. Map of San Francisco Area ................................................................................... 116

Figure 4-2. Educational Signs (used in treatment weeks) ........................................................ 117

Figure 4-3. MUWO Stated Choice Attributes ......................................................................... 119

Figure 4-4. Example of choice scenario................................................................................... 120

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LIST OF TABLES

Table 2-1. Details on survey questions, response values and how they relate to

understanding the visitor and sound perception. .............................................................. 44

Table 2-2 Multiple regression results for pleasantness ............................................................ 51

Table 3-1. Final GLMM models .............................................................................................. 87

Table 3-2. Observed relationship between each response variable and the model-

averaged parameters from the final models ..................................................................... 88

Table 3-3. Acceptability of hearing small aircraft sounds from recording #6 (flights per

hour) ................................................................................................................................. 91

Table 3-4. Acceptability of hearing aircraft sounds from recording #6 (times per day)

before respondent would no longer visit Denali .............................................................. 91

Table 3-5. Respondents bothered, disturbed, or annoyed by other aircraft ............................. 92

Table 4-1. Parameter Estimates for the Latent Class Model .................................................... 123

Table 4-2. Differences in marginal utility scores between the treatment and control

groups ............................................................................................................................... 124

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ACKNOWLEDGEMENTS

To be honest, this part of my dissertation has been more difficult to write than I expected.

It’s hard to put into words how grateful I am to have the two most supportive advisors, Drs. Peter

Newman and Derrick Taff. When I reflect on your mentorship, it spans more than ten years. You

both have been role models and guiding lights since my time as an undergraduate at Colorado

State. Thank you both for always having so much confidence in me. At times I was discouraged

by the challenges you threw my way, but those experiences have only strengthened my skillset, as

well as, my own self confidence. Peter, thanks for giving me the opportunity to conduct

meaningful research in parks and for always knowing when I needed a laugh or a nudge of

encouragement. It’s scary how well you know me—I thought I could hide my struggles, but you

know me all too well! Derrick, thank you for your selfless commitment to mentoring me through

the epic highs and lows of graduate school. Your guidance and advice has been invaluable! I want

to also thank both of you for making me feel like a part of your families. I admire your generous

and welcoming approach to mentorship.

I would also like to express my deep appreciation for my committee members, Drs.

Andrew Mowen and Justine Blanford. Andy, thank you for always putting time and effort toward

assisting me with either a class project, my exams, or writing my first journal article. You’ve

helped me realize my potential as a writer and researcher. Justine, thank you for your endless time

and dedication to my education. I can’t tell you how much I value your mentorship and words of

advice. To this day, when I find myself discouraged, a walk and a cup of tea help with finding a

new perspective.

I would also like to acknowledge the National Park Service Natural Sounds and Night

Skies Division and their support for social science acoustics research at Penn State. Special

thanks to Daniel Mennitt for his willingness to share data and insights. Data analysis would have

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been an extreme challenge without the help of Megan McKenna and Kurt Fristrup. I would still

be trying to figure out how to code in R if it wasn’t for Megan’s help. Your kindness and

generosity is deeply appreciated. Thank you for opening your home to me and for taking the time

to work though my data analysis with me.

I wouldn’t have gotten to this point in my education without the support of my husband,

Dr. Mike Ferguson. Thank you for being my biggest cheerleader and source of comfort. You’ve

been with me to celebrate the highs and lift me up during the lows, especially with chocolate and

coffee. Thanks for making me laugh and reminding me that this is recreation management and not

brain surgery. I think my stress levels would have been through the roof if you hadn’t been by my

side.

I would like to also thank my dear officemate and friend to the end, Jenn Newton for her

love and support. Your positive energy, intellect, and keen ability to read my mind made the

mundane grad school grind so much more enjoyable. Also, a huge high-five goes to Brian Soule

for being my best friend and roommate. Thanks for laughing with me (or at me) and dealing with

me at times when I was hangry. To the rest of the grad students, thanks for always having my

back and for making time spent both in class and out of class exciting.

I am grateful to have had funding and support from the National Park Service, as well as,

the opportunity to collaborate with accomplished researchers. Thank you to Shan Burson and

Davyvd Betchkal for having the kindness and patience to work with me on acoustics projects that

were way above my head. It has been a pleasure to conduct research in Denali National Park and

Preserve. I appreciated guidance from Denali managers Rose Keller and Dave Schirokauer.

Through the NSF project, I’ve been grateful for the opportunity to collaborate with Cal Poly and

Boise State Universities. Clinton Francis, Jesse Barber, and Mitchell Levenhagen, thank you for

your patience and encouragement…and for teaching me to play the most dangerous game I’ve

ever encountered, Stump.

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Finally, I would like to acknowledge my mom, dad, and Brother John. Thank you for

taking me to parks as a child and for showing me how to love the natural world. More

importantly thank you for your unconditional love and support. Thanks for always telling me how

proud you were of me, it was more motivating than you’ll ever know. Mom, thanks for proof

reading papers and survey instruments. You are the best proof-reader I know. Also, thanks for the

sweet care packages that always included candy and some type of stress reliever. Your coloring

books were my escape while studying for exams. I’m really lucky to have such an amazing

family.

Chapter 1

Introduction

Sound can simply be defined as a vibration that travels through a medium, most

commonly air, which is then heard by people or animals. The science of sound is studied by

multiple disciplines. Biologists and bioacustitions explore the impacts of sound on wildlife such

as birds and ocean mammals. Environmental psychologists study the impact of sound on human

cognition, emotion, and so on. Within the field of recreation management, researchers aim to

understand the impact of sound, both natural and anthropogenic, on visitor experiences in parks.

While sound is simply a vibration, noise is the negative or unwanted interpretation of sound. If

people travel to parks to enjoy the natural world, what are the outcomes of experiencing man-

made noise? This dissertation aims to explore different methodologies for measuring visitor

experiences with the acoustic environment in National Parks. The first paper explores the

relationship between one’s home sound level and their interpretation of soundscapes at Muir

Woods National Monument. The purpose of the second paper is to utilize a large suite of sound

clips to determine visitors’ threshold for propeller aircraft noise at Denali National Park and

Preserve. Finally, the third paper aims to test the tradeoffs visitors to Muir Woods National

Monument are willing to make in order to experience a more natural soundscape.

The National Park Service Organic Act (1916) established a system of protected National

Parks and outlined their objectives. The goal of the National Park Service (NPS) is twofold: to

protect resources, such as water and wildlife; and provide enjoyment for “future generations”. As

visitation to parks increases, so does anthropogenic or manmade sounds (NPS, 2000). Visitors are

traveling to parks in cars, trucks, and motorcycles. They are sightseeing in airplanes and

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helicopters. Additionally, areas within parks are becoming louder as a result of visitors talking,

using cellphones, and playing music on portable speakers. For the majority of park visitors,

hearing natural sounds is an important motivation for their park visit (Driver, Nash, & Hass,

1978; Marin, Newman, Manning, Vaske, & Stack, 2011; McDonald, Baumgartner, & Iachan,

1995). These increasing anthropogenic sounds can also impact wildlife by changing behavior and

breeding patterns (Francis & Barber, 2013). If the goal of the NPS is to protect resources and

provide enjoyment, increasing anthropogenic sounds are negating these goals. It is important for

park managers to measure and mitigate the acoustic environment or the soundscape, in order to

provide visitors with high quality experiences and benefits.

In a recent paper by Francis et al., (2017), natural sounds are described as benefits to

humans in the form of a psychological ecosystem service. The negative impacts of anthropogenic

sounds to human health and wellbeing are well documented. Prolonged exposure to these sounds

can cause hearing loss, increased stress and heart disease (Babisch, 2003). They can also reduce

cognitive function; which was found in children who attended school located in a noisy flight

path (Cohen, Evans, Krantz, & Stokols, 1980). Conversely, natural sounds can provide humans

with positive health outcomes. These recent studies have found that exposure to natural sounds

can improve cognition (Abbott, Taff, Newman, Benfield, & Mowen, 2016), mood (Benfield,

Taff, Newman, & Smyth, 2014) and recovery from stress (Alvarsson, Wiens, & Nilsson, 2010).

Based on this evidence, the benefits natural sounds provide humans are couched as an ecosystem

service. According to the Millennium Ecosystem Assessment (MA, 2005) an ecosystem service is

an entity derived from a natural ecosystem that benefits human wellbeing.

The increase in anthropogenic sounds which masks or reduces natural sounds can

influence human wellbeing through cultural or psychological ecosystem services like recreation,

aesthetic beauty, and reflection (Francis et al., 2017). Cultural ecosystem services are the non-

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tangible benefits provided by ecosystems through recreation, cognitive development, enjoying

natural beauty, enhancing spirituality and so on (MA, 2005). Whether we define natural sounds as

a cultural or psychological ecosystem service, the outcomes are similar. Measuring and

quantifying the impact of cultural ecosystem services can further justify the protection of natural

ecosystems, beyond just tangible needs like clean water (Daniel et al., 2012). For example, Fuller

et al. (2007) found that visitors to an urban park had increased measures of wellbeing when they

also perceived increased biodiversity. Planners and policy makers are beginning to recognize the

importance of ecosystem services and can use research that highlights these benefits to place

more funding and attention on protected areas that provide services (Bratman, Hamilton, & Daily,

2012).

National Parks are places where visitors can experience the benefits of the natural world,

which includes a soundscape rich in natural sounds with little interruption from man-made noise.

The purpose of this dissertation outline is to explore various methods for measuring and

managing soundscapes and their impacts to visitors. This research aims to assist managers in

maintaining natural quiet, to adhere to policy mandates, but also for the positive experiences and

benefits they provide through ecosystem services.

What is a soundscape?

A soundscape can be defined simply as the “acoustical environment” (Newman,

Manning, & Trevino, 2010, p. 2). The acoustic environment has been identified as an important

resource. Researchers from diverse disciplines study sounds and their impacts on both humans

and wildlife (Barber et al., 2011; Benfield, Taff, et al., 2014; Merchant et al., 2015; Pijanowski et

al., 2011). In the past, research on sound has focused on noise defined as unwanted sounds. A

more comprehensive approach to understanding the acoustic environment can be achieved by

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considering soundscapes rather than just noise. In this paper, the term soundscape refers to the

relationship between a landscape and the composition of its sound (Pijanowski et al., 2011). The

field of soundscape ecology classifies the soundscape into three types: geophony, biophony, and

anthrophony (Krause, Gage, & Joo, 2011). Geophony refers to the sounds produced by the

geophysical environment, such as, wind and flowing water. Biophony is the combination of

sounds produced by non-human living organisms, like birdsong for example. Anthrophony refers

to human made noise, such as, vehicle and aircraft sounds.

The Importance of Sounds

Noise and anthropogenic sounds have been found to negatively impact both humans and

wildlife (Francis & Barber, 2013; Goines & Hagler, 2007). For humans, exposure to excessive

environmental noise can cause negative health outcomes such as stress, inadequate sleep, heart

disease and hearing loss (Hammer, Swinburn, & Neitzel, 2014). Moreover, in the United States,

millions of people are exposed to noise that exceeds the recommended level and are therefore at

risk of heart disease and other negative health outcomes (Hammer et al., 2014). For wildlife,

noise can make it more difficult to find a mate, detect prey or another predator, and like humans,

increase stress (Francis & Barber, 2013).

There is increasing evidence that postulates the negative impacts of anthropogenic sounds

to human health and wellbeing. It is well known that loud noise can damage one’s hearing.

Babisch et al. (2003) found that prolonged exposure to anthropogenic sounds can cause hearing

loss, increased stress, and even heart disease. In another study, Cohen et al. (1980), found that

children who attend school in a direct flightpath have increased stress and lower cognitive ability

than children who attend a quiet school. As our society continues to urbanize, the risk for

prolonged exposure to loud anthropogenic sounds will increase.

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While a number of studies highlight the negative impact of anthropogenic noise,

researchers are beginning to understand the positive influence of natural sounds on human health

and wellbeing (Abbott et al., 2016; Alvarsson et al., 2010; Benfield et al., 2014). The theoretical

basis for these studies come from the idea that there is a positive relationship between the natural

environment and human wellbeing. One theory is Attention Restoration Theory (ART; Kaplan,

1995) and the other is Stress Restoration Theory (SRT; Ulrich, 1991). Early studies in both ART

and SRT test the impact of viewing natural environments. Studies that test the influence of natural

sounds, test the impact of the acoustic environment. The positive impact of natural sounds is

three-fold: cognitive, physiological, and affective (Abbott et al., 2016; Alvarsson et al., 2010;

Benfield et al., 2014). These are also the benefits that fit well within the context of cultural

ecosystem services (Francis et al., 2017).

Earlier mentioned was a study by Cohen et al. (1980) that determined children who

attend school in a direct flightpath underperform on mental tasks compared to children at quiet

schools. If overflights can decrease cognitive performance, what impact can natural sound have

on cognitive performance? Berman, Jonides, & Kaplan (2010) found that study participants who

walk in a natural area perform better on tasks than those who walk in an urban area. This study

didn’t control for the acoustic environment, however, sounds could be an important variable.

Abbott et al. (2016) controlled for the acoustic environment. They found that after a mentally

exhausting task, study participants who were exposed to natural sounds, like those heard in a

National Park, outperformed those who heard no sounds. These studies provide evidence for the

positive influence of natural sound on human cognition.

Natural sounds have been found to improve recovery from stress, which is evidence of

the positive physiological impact of natural sound. For instance, Alvarsson et al. (2010)

conducted a study that tested stress recovery through heart rate and skin conductance. They gave

study participants a difficult arithmetic task, which increased stress. They exposed participants to

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either natural or anthropogenic sounds. They found, through physiological measures of stress,

that natural sounds promoted a faster stress recovery. Exposure to anthropogenic sounds

increased stress levels. Prolonged stress can lead to heart disease and other negative health

outcomes (Hammer, Swinburn, & Neitzel, 2014). Exposure to natural sounds, like those in

National Parks (if managed appropriately), can provide a place to restore from the stress of daily

life.

Finally, natural sounds can have a positive influence on affect or mood. Benfield et al.

(2014), tested how exposure to different acoustic environments effects mood. Study participants

were asked to watch a disturbing video, mood was measured through the PANAS scale. Then,

they were exposed to either natural or anthropogenic sounds. Mood was tested again and they

found that participants exposed to natural sounds had significantly improved emotional state

compared to those exposed to anthropogenic sounds. This study provides evidence for the

positive impact of natural sound on human affect.

Natural Sound and Resource Protection

Noise in National Parks is increasing. In a place where human caused environmental

impacts are kept to an absolute minimum, natural sound is becoming overshadowed by human

induced noise (Lynch, Joyce, & Fristrup, 2011). According to the U.S. National Park Service

(NPS), “noise levels in park transportation corridors today are at 1,000 times the natural level”

(p.11). National parks and wilderness areas are places where one could expect to find silence or at

least an escape from noisy urban environments. Enjoying the sounds of nature, silence and

escaping noise are often the most common motivations for parks and protected area visitors

(Driver et al, 1987; McDonald et al., 1995). With increased visitation to these areas, the amount

of unwanted sounds from traffic, airplanes, helicopters, people, etc. has become a topic of

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concern. The NPS Soundscape Management Policy 4.9 states “the service will take action to

prevent or minimize all noise that, through frequency, magnitude, or duration, adversely affects

the natural soundscape or other park resources or values…” (NPS, 2006). National Park managers

are taking the steps to understand acceptable levels of noise and to mitigate noise so that natural

sounds are not compromised.

The National Parks Overflight Act passed in 1987, required the NPS to identify

“acceptable levels” of noise produced by overflights in parks (NPS). Aircraft noise in the Grand

Canyon National Park was examined, as it is a popular site for helicopter tours, and it was

discovered that all locations within the park were affected by noise (Mace, Bell, & Loomis,

1999). Mace, Bell, and Loomis (1999) studied the effects of helicopter noise on the visual quality

of landscapes in regard to feelings of tranquility and solitude. In this lab study, participants

viewed landscape photos of the Grand Canyon while being exposed to different sounds:

helicopter at two sound levels (40 dB(A) and 80 dB(A)) and natural sounds (wind, bird song,

babbling brooks, natural quiet). This study found that unwanted noise affected visual landscape

quality. Feelings of annoyance, solitude, and tranquility were also negatively swayed by

helicopter noise. Interestingly, the specific sound level (40 and 80 dB(A)) was unimportant, all

variables that addressed landscape perception were negatively influence by unwanted sound

regardless of level.

Designated wilderness is one of the highest levels of protection for public lands. Federal

wilderness areas are expected to provide “outstanding opportunities for solitude or a primitive

and unconfined type of recreation” (National Wilderness Preservation Act 1964, Section 2c).

Tarrant, Hass, and Manfredo (1995) evaluated the effects of overflights on visitors to wilderness

areas in Wyoming. This study used a dose exposure survey technique to gain an understanding of

how visitor characteristics influence evaluations of overflights. In this study, dose refers to the

number, proximity, and types of overflights encountered. Researchers concluded that respondents

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had strong negative attitudes towards hearing overflights and were slightly more affected by

hearing overflights than seeing them. Levels of solitude and tranquility were also decreased by

sounds of overflights. Furthermore, respondents who had previously visited the wilderness area,

had lower tolerance and a higher negative attitude towards overflights. Because this particular

analysis did not include actual recordings of sound levels that visitors experienced, it is important

to note that their response to overflights was dependent on participants’ tolerance for noise.

Indicators and Standards of Soundscape Quality

National parks use a specific framework for managing visitor use. Visitor Experience and

Resource Protection (VERP) is the carrying capacity framework that was developed for and

applied to the NPS (Manning, 2001). More recently an adaptation of visitor management

frameworks and collaboration between federal agencies has led to a more general Visitor Use

Management Framework (Interagency Visitor Use Management Council, 2016). The framework

has been developed to guide adaptive management practices for all federal land management

agencies. The framework is comprised of several elements. These are considered elements or

components rather than steps in a process. Unlike a recipe, the VERP framework is an iterative

and ongoing process. Essentially, an interdisciplinary team develops management objectives. A

management objective is a clear management goal based on policy and the type of recreation

experience being managed for. An indicator is a measurable variable based on the identified

management goal. These variables can be biophysical (environmental impacts) or

social/experiential (crowding), depending on management objectives. A standard is defined as the

minimum acceptable level of quality based on the indicator variable. Another way of thinking of

standards is as thresholds for quality. For example, a park might manage wilderness areas for

“solitude”. So if the management objective is solitude, an indicator of this management objective

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could be number of people on the trail. A standard can be identified by asking, what is the

minimum acceptable level of people on the trail? Indicators and standards are used to identify

thresholds for quality visitor experiences. Managers can then monitor these variables to maintain

recreation quality.

Soundscape quality has been assessed, using an empirical approach to carrying capacity.

Pilcher, Newman, and Manning (2008), used the normative approach to identify indicators and

standards of a quality soundscape in Muir Woods National Monument. Indicators were identified

by having participants listen to the sounds in the park (a listening exercise). Respondents listed

the sounds heard and their evaluation of each sound (acceptable vs. unacceptable/annoying vs.

pleasing). Sounds that were deemed annoying and unacceptable were considered indicators.

Noise from other visitors (talking, screaming, etc.) was considered an indicator of quality. In

order to determine a standard, the researchers created sound clips with varying levels of visitor

noise. The sound pressure level of noise was used to measure the standard. The minimum

acceptable level of visitor noise indicated a standard. Managers went on to monitor the park

soundscape and found that sound levels exceeded the standard. Thus, management actions were

taken to quiet the park (Stack et al., 2008).

Natural Sound as an Ecosystem Service

The Millennium Ecosystem Assessment (MA; 2005) aimed to analyze the state of ecosystem

changes around the world and assess their impacts on human wellbeing. The overall results from

the assessment and research outlined in this document are grim. Worldwide, ecosystem services

are declining, which is why it is important develop plans and policies to conserve important

ecosystems. According to the MA (2005) an ecosystem service is something derived from a

natural ecosystem that benefits human wellbeing. An example of an ecosystem service is clean

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air, because it allows for humans to breathe and not ingest harmful pollutants. Ecosystems are

natural systems comprised of plants, soil, wildlife, people, and microorganisms. The MA (2005)

defines 4 types of ecosystem services: (1) provisioning services like food and timber; (2)

regulating services like water quality, flood control, and climate; (3) cultural services like

recreation, aesthetic beauty, and spirituality; and (4) supporting services like nutrient cycling.

These are all ecosystem services that provide benefits to wellbeing.

The framework described by the MA (2005) is used for measuring and assessing

ecosystem services. There are three elements in the framework: (1) a change in divers that impact

biodiversity like increased population; (2) this leads to a change in biodiversity; (3) this leads to a

change in ecosystem services and the benefits they provide to human wellbeing. This framework

can occur across multiple scales (national and regional). Under this framework, natural sounds

can be influenced by changes in biodiversity, which are a result of development and increased

anthropogenic sounds. Sounds are a common pool resource. Once they are taken from the shared

natural system, they are difficult to replace. The increase in anthropogenic sounds and reduction

in natural sounds can influence human wellbeing through cultural ecosystem services like

recreation, aesthetic beauty, and reflection. The following papers with expand on this framework.

Cultural ecosystem services are the non-tangible benefits provided by ecosystems

through recreation, cognitive development, enjoying natural beauty, enhancing spirituality and so

on (MA, 2005). Miclu et al. (2013) conducted an extensive literature review of research related to

cultural ecosystem services. They found that the research was conducted by multiple different

disciplines and that the approach to cultural ecosystem services is diverse. Miclu et al. (2013)

note that cultural ecosystem services are subjective based on both individual and societal and

cultural differences. Additionally, this type of ecosystem service is often not associated with an

economic benefit (like housing value). Ultimately, there is a lack of consensus regarding this type

of ecosystem service. In their review they found that some papers claim a monetary value for

11

cultural ecosystem services (CES), while others argue against placing a monetary valuation on

them. Over half of the papers they reviewed addressed some kind of assessment related to CES

and mental wellbeing.

Researchers have developed tools for measuring the outcomes of land management

strategies on ecosystem services. For example, Goldstien et al. (2012) and Nelson et al. (2009)

use a GIS modeling software called INVEST to model various outcomes of different land use

scenarios. This software can account for CES, however in these examples they are focused on the

outcomes of development and conservation on provisioning and supporting ecosystem services.

The software can analyze both biophysical and monetary outcomes. Plieninger et al. (2010) argue

that it is difficult to assess biophysical and monetary values of CES and they need to be evaluated

for socio-cultural benefits. They measure the attitudes, beliefs and behaviors related to ecosystem

services. In their study, they asked participants to conduct a participatory mapping exercise of

their home village. They marked areas on the maps where they acquired CES like recreation,

spiritual, and aesthetic benefits. The researcher used autocorrelation spatial analysis techniques to

assess patterns related to CES.

In a recent paper, Bratman et al. (2016) coins the term, psychological ecosystem services.

This paper highlights the research and theory related to the positive relationship between humans

and natural environments. They discuss Biophilia, SRT and ART. They argue that the natural

world provides humans with positive mental outcomes like cognitive and stress recovery, which

should be considered a psychological ecosystem service. The paper postulates that valuating the

benefits of psychological ecosystem services will aid in persuading policy makers and planners to

place more funding in areas like park and garden development, places where people can gain the

benefits of psychological ecosystem services.

Natural sounds provide humans with improved wellbeing. Earlier this paper discussed the

positive influence of natural sound on cognition, physiology, and affect. Based on the definition

12

of an ecosystem service, natural sounds are absolutely a benefit to human health and wellbeing,

provided by the natural environment. I argue that natural sounds can fit under the umbrella of

both CES and psychological ecosystem services (PES). Natural sounds are an important part of

the recreation experience, a benefit of CES. As mentioned earlier, they are a significant

motivation for park visitors. I would argue that hearing natural sounds is one of the many benefits

of recreating outdoors. Natural sounds can also influence one’s aesthetic experience in the

outdoors. Wienzimmer et al. (2014), found that anthropogenic sounds decrease visitors’

assessment of the naturalness of a park view scape. Natural sounds are also non-material and

intangible benefits described by the definition of CES (Miclu et al., 2013).

The positive benefits of natural sound on improving stress, cognition, and mood, fit well

within the definition of a PES (Bratman et al., 2016). In Bratman et al.’s (2016) review of

literature related to the benefits of nature and mental health, they point out that most studies

compare a natural environment to a non-natural environment. The common denominator in the

natural environments tested in these studies is quiet. Natural quiet and sounds of nature are an

important aspect of natural ecosystems. They provided humans with mental benefits, like

restoration. Whether we choose to define natural sounds as a CES or PES, the main goal is to

continue to study their benefits.

Methods Used in Natural Resource Management

Stated Choice Modeling.

Stated choice modeling was initially used in market research to understand preferences in

product design (Louviere, Hensher, & Swait, 2000). This method is used to help researchers

understand how people evaluate choices and the tradeoffs they are willing to make in order to

13

obtain an ideal scenario. Respondents of stated choice surveys are asked to make a series of

distinct choices between two scenarios that have multiple levels of attributes. For example, when

buying a new car, one has the option of choosing from an overwhelming number of accessories

(i.e. leather interior, power windows, satellite radio, etc.). The method of stated choice modeling

can tell us about the types of choices and “trade-offs” a sample of consumers might make. These

results aid in more precise product development and manufacturing.

This method has also been applied to park and recreation management (Bullock &

Lawson, 2008; Newman, Manning, Dennis, & Mckonly, 2005; Pettebone et al., 2011). Rather

than measuring preferences for products, stated choice has been used to measure visitors’

preferences and tradeoffs for social, natural, and managerial experiences in parks. Newman et al.,

(2005) studied the tradeoffs of backcountry users in Yosemite National Park’s wilderness areas.

This study used a survey with paired comparisons to determine respondents rated signs of human

use at backcountry campsites to be an important indicator of quality. Moreover, this method

allowed for researchers to provide Yosemite National Park management with the results of the

model, which indicated that respondents were willing to deal with more stringent management in

order to gain quality in the appearance of campsites.

In another study, Bullock and Lawson (2008), used stated choice to understand visitor

preferences for management at Cadillac Mountain, in Acadia National Park. Attributes for

management conditions included varying levels of management interference, ranging from

freedom and open access to turning many visitors away from visiting the summit during busy

times. The study also included attributes for social conditions (the number of people on the trail)

and resource conditions that reflected varying levels of visitor caused environmental damage.

During data collection, respondents were presented scenarios that described a narrative of varying

attributes, as well as, a photo that portrays the attribute narrative. Results from this study

identified visitors’ preference towards protecting the environmental resources on the summit.

14

Additionally, they are in favor of rigorous management implications, but prefer the summit to be

open access. These findings allow for management to understand the specific preferences of

visitors to this iconic park summit.

Researchers have also used stated choice modeling to understand park visitor preferences

off the trail. Pettebone et al. (2011) used this method to investigate visitors’ preference for

traveling within the Bear Lake Road area of Rocky Mountain National Park. Due to increased

use, the NPS is using alternative transportation, like bus systems, to move visitors through parks.

This study analyzed varying attributes related to destination convenience, traffic and visitor

volume, and number of hikers on a trail. Photos were also utilized to depict different scenarios.

Results from this study found that visitors prefer to use their personal vehicles in the park. They

were willing to tradeoff using their personal vehicle and use the bus transportation to avoid

congestion on the roads and trails. These data were useful to managers who can then use this

information to design a transportation system and encourage visitors to use the bus rather than

deal with vehicle traffic.

Mapping soundscapes.

Noise maps have been developed using the measurement of sound levels produced by

traffic and other noise, incorporated with modeling techniques. In these models, sound levels

from a source are identified and outputs are predicted based on varying geospatial data like

elevation, as well as, physical elements of sound propagation. Noise maps that illustrate sound

propagation in a natural environment have used different methods for noise modeling. A GIS tool

called SPreAD-GIS (The Wilderness Society, San Francisco, CA) integrates data on topography,

land cover, and weather to predict sound events (Reed, Boggs, & Mann, 2012; Reed, Ph, Smith,

Boggs, & Mann, 2010). Researchers used this tool to map the potential noise impacts from oil

15

and gas compressors (Barber et al., 2011). Other noise modeling programs exist, such as, NMSim

(Wyle Laboratories, Inc., Arlington, VA) can be used to map the effects of overflights (Barber et

al., 2011; Plotkin, 2001). Another noise modeling program, CadnaA (DataKustik, Greifenberg,

Germany) is used for calculating and visualizing propagation of anthropogenic noise from roads,

railways, and aircraft. Previous studies have used it to model hikers exposure to transportation

noise (Park, Lawson, Kaliski, Newman, & Gibson, 2010) and the noise impacts of vehicles in

Glacier National Park (Barber et al., 2011).

Noise modeling methods are sufficient for predicting sound from powerful sources like

traffic or aircraft at specific locations. However, according to Mennitt et al. (2014), these methods

are impractical for mapping natural environments because of the unspecified number of sound

sources and their random spatial dispersion. Different from noise modeling software, a geospatial

modeling method was used to predict ambient sound pressure levels across the contiguous United

States (D. Mennitt et al., 2014). This method utilized 69 potential explanatory variables derived

from spatial data from categories such as climate, hydrology, land cover, etc. The predictive

strength of explanatory variables were derived using sound level measurements from 190

National Parks across the country. This method is useful in predicting the acoustic environment

on national and regional scales.

Within the context of natural resource management, researchers have used acoustic mapping

to estimate the effects of noise on both wildlife and park visitors. For example, researchers used a

sound propagation map to modeling mapping hikers’ exposure to transportation noise within the

Bear Lake corridor of Rocky Mountain National Park (Lawson, Kaliski, Newman, & Gibson,

2009). In another study, researchers determined that noise produced by snowmobiles impacted

vegetation cover, wilderness experience, and the spatial behavior of moose (Mullet, 2014).

16

Management Strategies

When extensive visitor use begins to degrade the quality of park resources, managers

use different strategies to improve or protect resources. Direct and indirect management

strategies are used to change visitors’ perceptions or behaviors towards resource

protection (Manning, 2011). Direct management strategies apply regulatory measures to

change visitor behavior, while indirect strategies aim to impact visitors’ decision-making

process to influence behavior (Manning, 2011). An example of a direct management

strategy would be closing a degraded area within a park. For example, Hockett, Marion,

& Leung, (2017), used various management techniques, including trail closure, to reduce

off-trail hiking at a highly visited urban park. Informational or educational signs are a

form of indirect management that can alter visitor attitudes or perceptions (Manning,

2003). In relation to managing soundscapes, indirect management, in the form of

educational signs have been studied (Stack et al., 2011; Taff et al., 2014). Stack et al.

(2011), found educational signs to be effective in lowering park sound levels and Taff et

al., (2014), used messaging in Sequoia National Park to improve visitors’ acceptability of

military aircraft noise. The results of these studies suggest that indirect management is

useful for shifting visitor behavior and perceptions of park soundscapes.

Summary

Overall this chapter provided an overview of theories, methodologies, and concepts

related to soundscapes, especially within the context of National Park management. It explored

17

the definition of soundscapes, the importance of natural sounds and wellbeing, natural sound as a

natural resource and the impacts of sound on the recreation experience. Moreover, ecosystem

services are defined and natural sounds are couched as a psychological ecosystem service.

Finally, the review examined stated choice modeling and acoustic mapping methods.

Dissertation Purpose and Structure

The purpose of this dissertation is to explore strategies for measuring and

managing the impacts of noise as it relates to human experience and ecosystem services. Chapter

one introduces the state of soundscapes research in terms of measurement and theory. Chapters 2

through 4 were written as stand-alone manuscripts that will later be submitted to relevant peer-

reviewed journals. Chapter 2 aims to understand the relationship between park visitors’ home

sound exposure in relation to their rating of the soundscape at Muir Woods National monument.

Chapter 3 utilized an innovative method for determining visitor thresholds for propeller aircraft

noise in Denali National Park and Preserve. Chapter 5 assessed visitor preferences for soundscape

management at Muir Woods National Monument. The 5th chapter summarizes the combined

results of the three dissertation studies. The following chapters aim to answer these six research

questions:

Chapter 2: Impacts on Visitor Perceptions of Soundscapes in Muir Woods National

Monument

1) What factors influence visitors’ perception of the soundscape in Muir Woods

National Monument?

2) How does the sound level of visitors’ home zip code area influence their park

soundscape perception?

18

Chapter 3: Aircraft Sound Management in Denali National Park and Preserve

3) How can researchers best inform the development of thresholds for

soundscape quality using dose response methodology?

4) What factors influence visitors’ perception of overflight audio clips?

Chapter 4: Visitor Preferences for Soundscape Management in Muir Woods

National Monument

5) What tradeoffs are visitors willing to make in order to hear natural sounds in

Muir Woods National Monument?

6) Are preferences different for visitors in a treatment group (signs present

asking visitors to maintain quiet) vs. a control group (all signs are covered)?

References

Abbott, L. C., Taff, D., Newman, P., Benfield, J., & Mowen, A. (2016). The influence of

natural sounds on attention restoration. Journal of Park and Recreation

Administration, 34(3), 5–15.

Aletta, F., & Kang, J. (2015). Soundscape approach integrating noise mapping

techniques: a case study in Brighton, UK. Noise Mapping, 2(1), 1–12.

https://doi.org/10.1515/noise-2015-0001

Alvarsson, J. J., Wiens, S., & Nilsson, M. E. (2010). Stress recovery during exposure to

nature sound and environmental noise. International Journal of Environmental

Research and Public Health, 7(3), 1036–1046.

19

https://doi.org/10.3390/ijerph7031036

Anderson, G. S., Rapoza, A. S., Fleming, G. G., & Miller, N. P. (2011). Aircraft noise

dose-response relations for national parks. Noise Control Engineering Journal,

59(July), 519. https://doi.org/10.3397/1.3622636

Axelsson, Ö., Nilsson, M. E., & Berglund, B. (2010). A principal components model of

soundscape perception. Journal of the Acoustical Society of America, 128(5), 2836–

2846. https://doi.org/10.1121/1.3493436

Babisch, W. (2003). Stress hormones in the research on cardiovascular effects of noise.

Noise & Health, 5(18), 1–11. https://doi.org/NO_DOI

Baranzini, A., Ramirez, J., Schaerer, C., & Thalmann, P. (2008). Hedonic methods in

housing markets: Pricing environmental amenities and segregation. Hedonic

Methods in Housing Markets: Pricing Environmental Amenities and Segregation,

(December), 1–278. https://doi.org/10.1007/978-0-387-76815-1

Barber, J. R., Burdett, C. L., Reed, S. E., Warner, K. A., Formichella, C., Crooks, K. R.,

… Fristrup, K. M. (2011). Anthropogenic noise exposure in protected natural areas:

Estimating the scale of ecological consequences. Landscape Ecology, 26(9), 1281–

1295. https://doi.org/10.1007/s10980-011-9646-7

Benfield, J. A., Nurse, G. A., Jakubowski, R., Gibson, A. W., Taff, B. D., Newman, P., &

Bell, P. A. (2014). Testing Noise in the Field: A Brief Measure of Individual Noise

Sensitivity. Environment and Behavior, 46(3), 353–372.

https://doi.org/10.1177/0013916512454430

20

Benfield, J. A., Taff, B. D., Newman, P., & Smyth, J. (2014). Natural Sound Facilitates

Mood Recovery. Ecopsychology, 6(3), 183–188.

https://doi.org/10.1089/eco.2014.0028

Berman, M. G., Jonides, J., and Kaplan, S. (2008). The cognitive benefits of interacting

with nature. Psychological Science, 19(12 ), 1207-1212.

Bratman, G. N., Hamilton, J. P., & Daily, G. C. (2012). The impacts of nature experience

on human cognitive function and mental health. Annals of the New York Academy of

Sciences, 1249(1), 118–136. https://doi.org/10.1111/j.1749-6632.2011.06400.x

Bratman, G. N., Hamilton, J. P., Hahn, K. S., Daily, G. C., & Gross, J. J. (2015). Nature

experience reduces rumination and subgenual prefrontal cortex activation.

Proceedings of the National Academy of Sciences of the United States of America,

112(28), 8567–72. https://doi.org/10.1073/pnas.1510459112

Bullock, S. D., & Lawson, S. R. (2008). Managing the “Commons” on Cadillac

Mountain: A Stated Choice Analysis of Acadia National Park Visitors’ Preferences.

Leisure Sciences, 30(February 2007), 71–86.

https://doi.org/10.1080/01490400701756436

Buxton, R. T., McKenna, M. F., Mennitt, D., Fristrup, K., Crooks, K., Angeloni, L., &

Wittemyer, G. (2017). Noise Pollution is pervasive in U.S. protected areas. Sceince,

356(6337), 531–533. https://doi.org/10. 1126/science.aah4783

Cai, M., Zou, J., Xie, J., & Ma, X. (2015). Road traffic noise mapping in Guangzhou

using GIS and GPS. Applied Acoustics, 87.

21

https://doi.org/10.1016/j.apacoust.2014.06.005

Casey, J. A., Morello-Frosch, R., Mennitt, D. J., Fristrup, K., Ogburn, E. L., & James, P.

(2017). Race/ethnicity , socioeconomic status , residential segregation , and spatial

variation in noise exposure in the contiguous United States. Environmental Health

Perspectives, 125(7), 1–10. https://doi.org/10.1289/EHP898

Chemtob, C., Roitblat, H. L., Hamada, R. S., Carlson, J. G., & Twentyman, C. T. (1988).

A cognitive action theory of post-traumatic stress disorder. Journal of Anxiety

Disorders, 2(3), 253–275. https://doi.org/10.1016/0887-6185(88)90006-0

Chew, Y. R., & Wu, B. S. (2016). A soundscape approach to analyze traffic noise in the

city of Taipei, Taiwan. Computers, Environment and Urban Systems, 59, 78–85.

https://doi.org/10.1016/j.compenvurbsys.2016.05.002

Cohen, S., Evans, G. W., Krantz, D. S., & Stokols, D. (1980). Physiological,

motivational, and cognitive effects of aircraft noise on children: moving from the

laboratory to the field. The American Psychologist, 35(3), 231–243.

https://doi.org/10.1037/0003-066X.35.3.231

Cottrell, S. P., & Meisel, C. (2003). Responsibility To Protect the Marine Environment

Among Scuba. Symposium A Quarterly Journal In Modern Foreign Literatures,

252–262.

Daniel, T. C., Muhar, A., Arnberger, A., Aznar, O., Boyd, J. W., Chan, K. M., ... & Grêt-

Regamey, A. (2012). Contributions of cultural services to the ecosystem services

agenda. Proceedings of the National Academy of Sciences, 109(23), 8812-8819.

22

De Coensel, B., & Botteldooren, D. (2007). The Quiet Rural Soundscape and How to

Characterize it, 92(August), 887–897. Retrieved from

papers3://publication/uuid/048B056A-E4B0-4544-B256-DD3146CFDC2F

Ferrini, S., & Scarpa, R. (2007). Designs with a priori information for nonmarket

valuation with choice experiments: A Monte Carlo study. Journal of Environmental

Economics and Management, 53(3), 342–363.

https://doi.org/10.1016/J.JEEM.2006.10.007

Fidell, S., Silvati, L., Howe, R., Pearsons, K. S., Tabachnick, B., Knopf, R. C., …

Buchanan, T. (1996). Effects of aircraft overflights on wilderness recreationists. The

Journal of the Acoustical Society of America, 100(5), 2909–2918.

https://doi.org/10.1121/1.417102

Francis, C. D., & Barber, J. R. (2013). A framework for understanding noise impacts on

wildlife: An urgent conservation priority. Frontiers in Ecology and the Environment,

11(6), 305–313. https://doi.org/10.1890/120183

Francis, C. D., Newman, P., Taff, B. D., White, C., Monz, C. A., Levenhagen, M., …

Barber, J. R. (2017). Acoustic environments matter: Synergistic benefits to humans

and ecological communities. Journal of Environmental Management, 203, 245–254.

https://doi.org/10.1016/j.jenvman.2017.07.041

Freimund, W. a., Vaske, J. J., Donnelly, M. P., & Miller, T. a. (2002). Using Video

Surveys to Access Dispersed Backcountry Visitors’ Norms. Leisure Sciences, 24(3–

4), 349–362. https://doi.org/10.1080/01490400290050790

23

Freimund, W. A., Vaske, J. J., Donnelly, M. P., & Miller, T. A. (2002). Using video

surveys to access dispersed backcountry visitor’s norms. Leisure Sciences, 24(3–4),

349–362. https://doi.org/10.1080/01490400290050790

Goines, L., & Hagler, L. (2007). Noise pollution: a modern plague. Southern Medical

Journal, 100(3), 287–294. https://doi.org/10.1097/SMJ.0b013e3180318be5

Goldstein, J. H., Caldarone, G., Duarte, T. K., Ennaanay, D., Hannahs, N., Mendoza, G.,

... & Daily, G. C. (2012). Integrating ecosystem-service tradeoffs into land-use

decisions. Proceedings of the National Academy of Sciences, 201201040.

Haas, G. E., & Wakefield, T. J. (1998). National parks and the American public: a

national public opinion survey on the National Park System: a summary report. The

Association.

Hammer, M. S., Swinburn, T. K., & Neitzel, R. L. (2014). Environmental noise pollution

in the United States: Developing an effective public health response. Environmental

Health Perspectives, 122(2), 115–119. https://doi.org/10.1289/ehp.1307272

Heywood, J. L., Murdock, W. E., Heywood, J. L., & Murdock, W. E. (2002). Social

Norms in Outdoor Recreation : Searching for the Behavior-Condition Social Norms

in Outdoor Recreation : Searching for the Behavior-Condition Link, (912280237),

283–295. https://doi.org/10.1080/01490400290050745

Hong, J. Y., & Jeon, J. Y. (2014). Soundscape mapping in urban contexts using GIS

techniques. Inter-Noise 2014, 5.

24

Inglis J., G., Johnson I., V., & Ponte, F. (1999). Crowding norms in marine settings: A

case study of snorkelling on the Great Barrier Reef. Environmental Management,

24(3), 369–381.

Kaplan, S. (1995). The restorative benefits of nature: Toward an integrative framework.

Journal of Environmental Psychology, 15(3), 169–182.

https://doi.org/10.1016/0272-4944(95)90001-2

Kaplan, S. (1995). The restorative effects of nature: Toward an integrative framework.


https://doi.org/02724944/95/030169+14§12.00/0

Krause, B., Gage, S. H., & Joo, W. (2011). Measuring and interpreting the temporal

variability in the soundscape at four places in Sequoia National Park. Landscape

Ecology, 26(9), 1247–1256. https://doi.org/10.1007/s10980-011-9639-6

Kuss, F. R., Graefe, Alan, R., & Vaske, J. J. (1990). Visitor Impact Management: A

Review of Research.

Lee, S. W., Chang, S. Il, & Park, Y. M. (2008). Utilizing noise mapping for

environmental impact assessment in a downtown redevelopment area of Seoul,

Korea. Applied Acoustics, 69(8), 704–714.


Lex Brown, A. (2012). A review of progress in soundscapes and an approach to

soundscape planning. International Journal of Acoustics and Vibrations, 17(2), 73–

81. https://doi.org/10.20855/ijav.2012.17.2302

25

Liu, J., Kang, J., Luo, T., Behm, H., & Coppack, T. (2013). Spatiotemporal variability of

soundscapes in a multiple functional urban area. Landscape and Urban Planning,

115, 1–9. https://doi.org/10.1016/j.landurbplan.2013.03.008

Louviere, J. J., Hensher, D. A., & Swait, J. D. (2000). Stated choice methods: analysis

and applications. Cambridge university press.

Lynch, E., Joyce, D., & Fristrup, K. (2011). An assessment of noise audibility and sound

levels in US National Parks. Landscape Ecology, 26(9), 1297.

Ma, M. E. A. (2005). Ecosystems and human well-being: current state and

trends. Millennium Ecosystem Assessment, Global Assessment Reports.

Mace, B. L., Bell, P. a., & Loomis, R. J. (2004). Visibility and Natural Quiet in National

Parks and Wilderness Areas: Psychological Considerations. Environment &

Behavior, 36(1), 5–31. https://doi.org/10.1177/0013916503254747

Mace, B. L., Bell, P. A., & Loomis, R. J. (1999). Aesthetic , A V ective , and Cognitive E

V ects of Noise on Natural Landscape Assessment. Society, 1920(July 1998), 225–

242. https://doi.org/10.1080/089419299279713

Mace, B. L., Corser, G. C., Zitting, L., & Denison, J. (2013). Effects of overflights on the

national park experience. Journal of Environmental Psychology, 35, 30–39.

https://doi.org/10.1016/j.jenvp.2013.04.001

Manning, R. E. (2001). Programs That Work Visitor Experience and Resource

Protection: A Framework for Managing the Carrying Capacity of National Parks.

26

Joumal of Park and Recreation Administration, 19(1), 93–108.

Manning, R. E., & Freimund, W. A. (2004). Use of visual research methods to measure

standards of quality for parks and outdoor recreation. Journal of Leisure Research,

36(4), 557–579.

Manning, R. E. (2011). Studies in outdoor recreation. Corvallis, OR: Oregon St ate

University Press.

Marin, L. D., Newman, P., Manning, R., Vaske, J. J., & Stack, D. (2011). Motivation and

Acceptability Norms of Human-Caused Sound in Muir Woods National Monument.

Leisure Sciences, 33(931379096), 147–161.

https://doi.org/10.1080/01490400.2011.550224

McAlexander, T. P., Gershon, R. R. M., & Neitzel, R. L. (2015). Street-level noise in an

urban setting: Assessment and contribution to personal exposure. Environmental

Health: A Global Access Science Source, 14(1), 1–10.

https://doi.org/10.1186/s12940-015-0006-y

McDonald, C. D., Baumgartner, R. M., & Iachan, R. (1995). National Park Service

aircraft management studies. Report No. 94–2, US Department of the Interior.

Mennitt, D., Fristrup, K., Sherrill, K., & Nelson, L. (2013). Mapping sound pressure

levels on continental scales using a geospatial sound model. Internoise, (January),

1–11. https://doi.org/10.1371/journal.pone.0004065

Mennitt, D. J., & Fristrup, K. M. (2016). In fl uential factors and spatiotemporal patterns

27

of environmental sound levels in the contiguous United States, (May).

Mennitt, D., Sherrill, K., & Fristrup, K. (2014). A geospatial model of ambient sound

pressure levels in the contiguous United States. The Journal of the Acoustical

Society of America, 135(5), 2746–64. https://doi.org/10.1121/1.4870481

Merchant, N. D., Fristrup, K. M., Johnson, M. P., Tyack, P. L., Witt, M. J., Blondel, P., &

Parks, S. E. (2015). Measuring acoustic habitats. Methods in Ecology and Evolution,

6(3), 257–265. https://doi.org/10.1111/2041-210X.12330

Milcu, A. I., Hanspach, J., Abson, D., & Fischer, J. (2013). Cultural ecosystem services:

a literature review and prospects for future research. Ecology and Society, 18(3).

Miller, N. (2003). Transportation noise and recreational lands. Noise/News International,

9–21. Retrieved from http://www.hmmh.com/cmsdocuments/N011.pdf

Miller, N. P. (1999). The effects of aircraft overflights on visitors to US National Parks.

Noise Control Engineering Journal, 47(3), 112–117.

https://doi.org/10.3397/1.599294

Miller, N. P. (2008). US National Parks and management of park soundscapes: A review.

Applied Acoustics, 69(2), 77–92. https://doi.org/10.1016/j.apacoust.2007.04.008

Mullet, T. C. (2014). Effects of snowmobile noise and activity on a boreal ecosystem in

southcentral Alaska. ProQuest Dissertations and Theses, 261.

https://doi.org/10.1007/s13398-014-0173-7.2

National Park Service (2006). National Park Service Management Policies. U.S.

28

Government Printing Office. ISBN 0-16-076874-8.

Nelson, E., Mendoza, G., Regetz, J., Polasky, S., Tallis, H., Cameron, D., ... & Lonsdorf,

E. (2009). Modeling multiple ecosystem services, biodiversity conservation,

commodity production, and tradeoffs at landscape scales. Frontiers in Ecology and

the Environment, 7(1), 4-11.

Newman, P., Manning, R., Donald, D., & Mckonly, W. (2005). Decision Making in

Yosemite National Park , USA Using Stated Choice Modeling. Journal of Park and

Recreation Administration, 23(1), 75–89.

Newman, P., Manning, R., & Trevino, K. (2010). From landscapes to soundscapes:

Introduction to the special issue. Park Science, 26(3), 2-5.

Park, L., Lawson, S., Kaliski, K., Newman, P., & Gibson, A. (2010). Modeling and

mapping hikers ’ exposure to transportation noise in Rocky Mountain National Park.

Park Science, 26(3), 1–11. Retrieved from http://nova.wh.whoi.edu/palit/Park et

al_2010_Park Science_Modeling and mapping hikers ? exposure to transportation

noise in Rocky Mountain National Park.pdf

Park, L. O., Manning, R. E., Marion, J. L., Lawson, S. R., & Jacobi, C. (2008). Managing

Visitor Impacts in Parks : A Multi-Method Study of the Effectiveness of Alternative

Management Practices. Journal of Park and Recreation Administration, 26(1), 97–

121.

Pettebone, D., Newman, P., Lawson, S. R., Hunt, L., Monz, C., & Zwiefka, J. (2011).

Estimating visitors’ travel mode choices along the Bear Lake Road in Rocky

29

Mountain National Park. Journal of Transport Geography, 19(6), 1210–1221.

https://doi.org/10.1016/j.jtrangeo.2011.05.002

Pijanowski, L., Villanueva-rivera, B. C., Dumyahn, S. L., Farina, A., Krause, B. L.,

Napoletano, B. M., … Pieretti, N. (2011). SoundScape Ecology : The Science of

Sound in tiie Landscape, 61(3), 203–216.

Pilcher, E. (2006). Visitor Experience and Soundscapes : Annotated Bibliography. Noise

Control Engineering.

Pilcher, E. J., Newman, P., & Manning, R. E. (2009). Understanding and managing

experiential aspects of soundscapes at muir woods national monument.

Environmental Management, 43(3), 425–435. https://doi.org/10.1007/s00267-008-

9224-1

Plotkin, K. J. (2001). The Role of Aircraft Noise Simulation Models. The 2001

International Congress and Exhibition on Noise Control Engineering, 10(1).

Rapoza, A., Sudderth, E., & Lewis, K. (2015). The relationship between aircraft noise

exposure and day-use visitor survey responses in backcountry areas of national

parks. Journal of the Acoustical Society of America, 138(4).

https://doi.org/10.1121/1.4929934

Reed, S. E., Boggs, J. L., & Mann, J. P. (2012). A GIS tool for modeling anthropogenic

noise propagation in natural ecosystems. Environmental Modelling and Software,

37, 1–5. https://doi.org/10.1016/j.envsoft.2012.04.012

30

Reed, S. E., Ph, D., Smith, D. H., Boggs, J. L., & Mann, J. P. (2010). SPreAD-GIS : an

ArcGIS toolbox for modeling the propagation of engine noise in a wildland setting

The Wilderness Society SPreAD-GIS : an ArcGIS toolbox for modeling the

propagation of engine noise in a wildland setting, (2688), 1–27.

Riper, C. J. Van, Manning, R. E., Monz, C. A., & Goonan, K. A. (2011). Tradeoffs

Among Resource, Social, and Managerial Conditions on Mountain Summits of the

Northern Forest. Leisure Sciences, 33(April 2017), 228–249.

https://doi.org/10.1080/01490400.2011.564924

Rose, J. M., & Bliemer, Mi. C. J. (2009). Constructing efficient stated choice

experimental designs. Transport Reviews, 29(5), 587–617.

https://doi.org/10.1080/01441640902827623

Schomer, P., Mestre, V., Schulte-Fortkamp, B., & Boyle, J. (2013). Respondents’

answers to community attitudinal surveys represent impressions of soundscapes and

not merely reactions to the physical noise. The Journal of the Acoustical Society of

America, 134(1), 767–772. https://doi.org/10.1121/1.4808075

Shannon, G., Crooks, K. R., Wittemyer, G., Fristrup, K. M., & Angeloni, L. M. (2016).

Road noise causes earlier predator detection and flight response in a free-ranging

mammal. Behavioral Ecology, 27(5), 1370–1375.

https://doi.org/10.1093/beheco/arw058

Shavelson, R. J. (2004). Editor’s Preface to Lee J. Cronbach’s “My Current Thoughts on

Coefficient Alpha and Successor Procedures”Lee J. Cronbach 1916-2001.

31

Educational and Psychological Measurement, 64(3), 389–390.

https://doi.org/10.1177/0013164404264117

Shelby, B., Vaske, J. J., & Donnelly, M. P. (1996). Shelby et al (1996) - Norms,

standards _ natural resources.pdf.

Stack, D. W., Peter, N., Manning, R. E., & Fristrup, K. M. (2011). Reducing visitor noise

levels at Muir Woods National Monument using experimental management. The


https://doi.org/10.1121/1.3531803

Stankey, G. H., Cole, D. N., Lucas, R. C., Petersen, M. E., & Frissell, S. S. (1984). The

limits of acceptable change (LAC) system for wilderness planning: Volume 176 of

General technical report INT. General Technical, 176, 37.

Taff, D., Newman, P., Lawson, S. R., Bright, A., Marin, L., Gibson, A., & Archie, T.

(2014). The role of messaging on acceptability of military aircraft sounds in Sequoia

National Park. Applied Acoustics, 84, 122–128.


Tarrant, M. A., Haas, G. E., & Manfredo, M. J. (1995). Factors Affecting Visitor

Evaluations of Aircraft Overflights of Wilderness Areas. Society & Natural

Resources, 8(4), 351–30.

Theebe, M. A. J. (2004). Planes, Trains, and Automobiles: The Impact of Traffic Noise

on House Prices. The Journal of Real Estate Finance and Economics, 28(2/3), 209–

234. https://doi.org/10.1023/B:REAL.0000011154.92682.4b

32

Trojanek, R., Tanas, J., Raslanas, S., & Banaitis, A. (2017). The Impact of Aircraft Noise

on Housing Prices in Poznan. Sustainability, 9(11), 2088.

https://doi.org/10.3390/su9112088

United States Congress (1916). The National Park Service Organic Act. National Park Service,

16(9).

Vaske, J. J., Donnelly, M. P., & Lehto, X. (2002). Visitor crowding and normative

tolerances at congested areas of Rocky Mountain National Park. HDNR Unit

Report, 50, 50.

Weinzimmer, D., Newman, P., Taff, D., Benfield, J., Lynch, E., & Bell, P. (2014).

Human responses to simulated motorized noise in national parks. Leisure Sciences,

36(3), 251–267. https://doi.org/10.1080/01490400.2014.888022

Wilson, E. O. (2001). Nature matters. American Journal of Preventive Medicine, 20(3),

241–242. https://doi.org/10.1016/S0749-3797(00)00318-4

33

Chapter 2 Impacts on Visitor Perceptions of Soundscapes in Muir Woods National

Monument

Chapter 2 was written as a stand-alone manuscript that will later be modified for

submission to a peer-reviewed journal. This article seeks to answer:

Q1: What factors influence visitors’ perception of the soundscape in Muir Woods

National Monument?

Q2: How does the sound level of visitors’ home zip code area influence their park


Abstract: Unwanted sounds from man-made sources, defined as noise, are rising both in

our home environments as well as in our Natural Parks. Noise pollution can affect the

health and welfare of many mammals, including humans. As a result, National Parks aim

to protect, maintain and restore natural sounds for the health and wellbeing of wildlife, as

well as visitor experiences. For most visitors hearing the sounds of nature and

experiencing natural quiet are important motivations. Ensuring that visitors obtain these

benefits they expect are important. However, each individual has a unique perception of

their soundscape that can be influenced by a variety of factors such as their motivation

for visiting the park or personal norms and attitudes related to specific sound sources.

These in turn influences how one perceives sounds heard in a park setting. The purpose

of this study is to better understand soundscape perceptions in parks and identify how

different factors may influence these perceptions. Data on visitors’ perceptions of the

soundscape when visiting Muir Woods, north of San Francisco, were collected during

May 2016 and compared to the sounds of their home environments. A linear multiple

34

regression model was applied to the data and showed that visitors who came from noisier

zip codes perceived the park to be less pleasant. Through a better understanding of how

personal factors might influence a visitors’ perspective of a soundscape, findings from

this study can help park managers manage visitor experiences and expectations.

Introduction

Humans have the ability to close their eyes, but are never able to close their ears.

In urban areas, noise from traffic, overflights, construction, and other man-made sounds

are potentially inescapable at all hours of the day. In fact, more than eighty percent of the

contiguous United States has elevated sound pressure levels caused by noise (Mennitt,

Fristrup, Sherrill, & Nelson, 2013). Extensive exposure to noise can negatively affect

human health by elevating blood pressure levels and promoting stress and heart disease

(Goines & Hagler, 2007; Hammer et al., 2014). Parks and protected areas serve as places

where visitors can find refuge from everyday noise, however, a recent study found that

63% of protected areas experience elevated man-made noise (Buxton et al., 2017). Thus,

protecting natural sounds in parks is important, especially as visitors to parks and

protected areas are seeking natural sound experiences as a sanctuary from potentially

loud and noisy soundscapes they might experience at home.

Humans have an innate biological association to the natural world (Wilson, 1984)

that is also of value for healing the mind and body as captured by famous nature writers

such as Muir (1901; 1979) and Thoreau (1854), as well as, documented by many

researchers across disciplines (Abbott, Taff, Newman, Benfield, & Mowen, 2016;

35

Benfield, Taff, Newman, & Smyth, 2014; Ulrich, 1993; Wilson, 2001). The positive

relationship between human health and spending time in nature can promote improved

memory retention (Holden and Mercer, 2014) and overall psychological wellbeing. For

example, Attention Restoration Theory suggests the natural environment can facilitate

recovery from mental fatigue (Kaplan, 1995) while Stress Restoration Theory, posits

natures’ effect on restoring emotional and physiological responses to stress (Ulrich, 1984)

and lead to a reduction in repetitive negative thoughts (Bratman, Hamilton, Hahn, Daily,

& Gross, 2015). The main focus of these studies was on the visual elements that

environments provided, however, environments are multi-dimensional and also

comprised of soundscapes.

A soundscape can be defined simply as the “acoustical environment” (Newman,

Manning, & Trevino, 2009, p. 2) that is the relationship between a landscape and the

composition of its sound (Pijanowski et al., 2011). Soundscapes can be comprised of

three types: geophony, biophony, and anthrophony (Figure 2-1; Krause, Gage, & Joo,

2011). Geophony refers to the sounds produced by the geophysical environment, such as

wind and flowing water; biophony is a combination of sounds produced by non-human

living organisms, such as birds, wild animals, frogs and insects; and anthrophony refers

to human made noises that include talking, vehicle and aircraft sounds.

36

Figure 2-1 Summary of Soundscape Elements that are comprised of sounds that are natural

(geophony), flora and fauna (biophony) and/or human-made (anthrophony)

Noise and anthropogenic sounds can negatively impact both humans and wildlife

(Francis & Barber, 2013; Goines & Hagler, 2007). Excessive exposure to environmental

noise can cause negative health outcomes such as stress, inadequate sleep, heart disease

and hearing loss in humans (Hammer et al., 2014) (Figure 2-3). Prolonged exposure to

noise levels above 75 dB(A) have the ability to damage the inner ear and cause hearing

loss (See Figure 2-2; reviewed in Hammer et al., 2014). In fact, Hammer et al. (2014),

estimate that a large portion of U.S. residents are subject to higher levels of noise and

therefore subject to noise-related health problems. For wildlife negative effects of noise

may include difficulty in finding a mate, detecting prey or predators, as well as, increased

stress (Francis & Barber, 2013).

Geophony

- Wind

- Water

- Trees blowing in the wind

Biophony

- Birdsong

- Elk Bugal

-Small mammals

Anthrophony

- Overflights

- Traffic

- Human voices

37

Figure 2-2. Estimation of sound levels and common sounds (adapted from NPS, 2008)

Figure 2-3. The positive and negative effects natural and anthropogenic sound can have on the

wellbeing of humans.

38

Just as viewing built environments fail to contribute to psychological wellbeing,

exposure to anthropogenic sounds impede positive health outcomes. Urban soundscape

sources such as aircraft, traffic, and people talking have been found to interfere with

memory (Benfield et al., 2010) and assessments of landscape beauty (Weinzimmer et al.,

2014). Additionally, Cohen et al. (1980), found that children who attend school in a direct

flightpath have increased stress and lower cognitive ability than children who attend a

quiet school. As our society continues to urbanize, the risk for prolonged exposure to

loud anthropogenic sounds will rise.

The negative impacts related to urban noise exposure paint a grim picture,

however, researchers have also focused on highlighting the positive benefits of exposure

to natural sounds. Natural soundscapes including biophony, such as birdsong; and

geophony, such as wind and running water. These sounds are important resources to the

health and well-being of both humans and wildlife (Francis et al., 2017). Natural sounds

have been found to improve human cognition (Abbott et al., 2016), enhance positive

moods (Benfield et al., 2014), and increase recovery from stress (Alvarsson et al., 2010)

(Figure 2). For wildlife, natural sounds play an important role in reproduction and safety

and the detection of prey (Francis et al., 2017).

The relationship between humans and soundscapes is complex. Smith &

Pijanowski (2014), presented a framework for better understanding this relationship that

employs methods from health, psychology, economics, and anthropology. By better

understanding the impacts of anthropogenic sounds on various elements of human

existence, researchers can provide empirical evidence that drives changes in management

and policy for protecting natural soundscapes. One example from this framework is the

39

impact of anthropogenic noise on housing value. Several studies have shown that

increased levels of transportation or other forms of man-made noise decrease housing

values (Baranzini, Ramirez, Schaerer, & Thalmann, 2008; Theebe, 2004; Trojanek,

Tanas, Raslanas, & Banaitis, 2017). Additionally, the presence of bird diversity correlates

with higher housing values. This suggests that natural sound, in the form of birdsong, can

also influence economic drivers like housing value.

To understand the complexity of soundscapes, geospatial tools and analyses that

visually represent acoustic environments are increasingly being used to understand

landscapes and capture noise from unwanted sound sources such a traffic or construction.

Visual representations of the acoustic environment have been used to demonstrate the

distribution of computed sound pressure levels in a specific area (Hong & Jeon, 2014).

These maps are useful for depicting sound pressure levels and the dispersion of these

sounds through the landscape from its source. For example, researchers developed noise

maps in Seol, Korea to predict the noise impact from new building development (Lee,

Chang, & Park, 2008). At a much larger scale, a noise map was used to estimate the

extent of transportation noise across the United States (N. Miller, 2003).

Geospatial modeling has been used to create maps that measure natural sound

levels and the impact of anthropogenic sounds throughout the contiguous United States

(Mennitt et al., 2013). These models that predict sounds across the country have also

been used recently to understand the amount of noise pollution prevalent in protected

areas (Buxton et al., 2017) and racial, ethnic, and social inequalities in relation to noise

pollution (Casey et al., 2017). Although soundscape maps integrate information collected

through a variety of devices (e.g. (Mennitt et al., 2013), a more holistic approach to

40

understanding the acoustic environment can also include human perception of sound

where people rate sounds (Aletta & Kang, 2015; Hong & Jeon, 2014; Brown, 2012) that

capture not only anthropogenic noise, but sounds from sources such as birds, water, and

wind (Aletta & Kang, 2015; Chew & Wu, 2016; Hong & Jeon, 2014; Brown, 2012).

Noise maps are used to measure exposure, as well as, identify problem areas where

mitigation is needed (Aletta & Kang, 2015; Brown, 2012) and have been useful for

developing policies that aim to regulate and manage noise (Murphy & King, 2010) so as

to minimize negative impacts (Aletta & Kang, 2015; Cai, Zou, Xie, & Ma, 2015; Hong &

Jeon, 2014; Lee et al., 2008; Liu, Kang, Luo, Behm, & Coppack, 2013; Shavelson, 2004)

Within the context of natural resource management, acoustic mapping has been

used to estimate the effects of noise on both wildlife and park visitors. These have

included sound propagation maps to model hikers’ exposure to transportation noise

within the Bear Lake corridor of Rocky Mountain National Park (Park, Lawson, Kaliski,

Newman, & Gibson, 2010) and the impact of vegetation cover on noise produced by

snowmobiles wilderness experience and the spatial behavior of moose (Mullet, 2014).

For most visitors to parks and protected areas, hearing the sounds of nature and

experiencing natural quiet are important motivations for their visit (Haas & Wakefield,

1998). As visitation to these iconic parks increase, so do sounds from transportation and

other visitors. Unwanted sounds from man-made sources, defined as noise, are increasing

in National Parks (NPS, 2010). As a result, National Parks have plans and polices in

place to protect, maintain and restore natural sounds (e.g. the Director’s Order #47,

Soundscape Preservation and Noise Management, 2000) and quiet for both visitor

experiences and wildlife health and wellbeing.

41

Several studies have explored factors that influence perceptions of soundscapes

(Axelsson, Nilsson, & Berglund, 2010; Benfield, Nurse, et al., 2014; Cottrell & Meisel,

2003; De Coensel & Botteldooren, 2007; Marin et al., 2011; Schomer, Mestre, Schulte-

Fortkamp, & Boyle, 2013). A previous study found that motivations can influence

visitors’ perceptions of the soundscape (Marin et al., 2011). Within the environmental

noise literature, it has been concluded that people in different communities perceive

identical sounds to be either less annoying or more annoying based on their personal

norms and attitudes (Schomer et al., 2013).

Based on previous studies, motivations (Marin et al., 2011) and noise sensitivity

(Benfield et al., 2014) can predict visitors’ perceptions of the soundscape they experience

in National Parks. To date, no study has explored the role of visitors’ home sound

exposure in predicting their attitude towards the park soundscape. Therefore, the research

questions related to this study are: What factors influence visitors’ perception of the

soundscape in Muir Woods National Monument? And how does the sound level of

visitors’ home zip code area influence their park soundscape perception?

Methods

Study Area

Muir Woods National Monument (MUWO) is located north of San Francisco,

California (See Figure 2-4). MUWO is a popular destination for tourists and includes 500

acres of redwood trees, with hiking trails throughout. Visitation to the park has been

steadily increasing and exceeds one million visits per year (NPS, 2017). Due to the high

42

visitation rates at this relatively small park, reservations are now required for all personal

vehicles and shuttle riders visiting MUWO. People are drawn to this park to experience

the towering and awe inspiring old growth coastal redwood forest. MUWO is keen on

protecting its natural sounds and since 2005, the park has supported a variety of

soundscape studies (Marin et al., 2011; E. Pilcher, 2006; Stack, Peter, Manning, &

Fristrup, 2011) that examined the effectiveness of signage to reduce visitor noise (Stack

et al., 2011). Due to the findings from this study the park now has a “quiet zone” in the

Cathedral Grove area of the park.

Figure 2-4. Muir Woods National Monument (MUWO), the study area, is located X km north of

San Francisco, California

43

Survey Data

A total of 537 surveys were collected between May 9th and 21st, 2016 as visitors

were exiting the park. The primary purpose of the survey was to collect information

about how noise influences visitors’ soundscape experiences. Similar to Stack et al.’s

(2011) study, the survey evaluated the effectiveness of realistic management solutions to

improving environmental conditions for wildlife and visitor experiences in Muir Woods

National Monument (MUWO). In addition, data were also collected to examine what

visitors were willing to tradeoff to achieve a high quality acoustic experience. For the

purpose of this paper, we focused on questions specific to visitors’ perceptions of the

soundscape in MUWO that capture pleasantness, noise sensitivity and ability to hear

natural sounds (Table 2-1). In addition, visitors were asked about their motivation for

visiting the park from one to six with one being “not relevant” and six being “extremely

important” and where they came from, by including a zip code. This was examined to

better understand the purpose of the visit and distance traveled.

44

Table 2-1. Details on survey questions, response values and how they relate to understanding the

visitor and sound perception.

Question Value Range

Motivation Please rate the importance of each of the

following reasons for your visit to Muir

Woods National Monument today.

1 (not relevant)

6 (extremely important)

Geographic

location

What is your home zip code? Enter zip code

Perceptions of the soundscape

Pleasantness Visitors hear a lot of sounds, including

natural sounds and human-made sounds.

Based on your experiences today, how

would you rate your pleasantness of the

soundscape?

1 (very unpleasant)

6 (very pleasant)

Noise

sensitivity

scale

1) I am sensitive to noise

2) I find it hard to relax in a place that’s

noisy.

3) I get mad at people who make noise that

keeps me from falling asleep or getting

work done.

4) I get annoyed when my neighbors are

noisy.

I get used to most noises without much

difficulty (reverse coded).

1 (strongly disagree)

6 (strongly agree)

Ability to

hear natural

sounds

Based on your experience today, how well

were you able to hear natural sounds?

1 (almost always clearly

without interference

from human-made

sound)

5 (almost always with

interference from

human-made sounds)

Pleasantness - In most park-related soundscape studies, visitors are asked to rate

the acceptability of the soundscape, as well as, their interpretation of the soundscape (a

scale from pleasing to annoying) (Marin et al., 2011; Stack et al., 2011; Taff et al., 2014).

Together these questions are measuring individuals’ perceptions and attitudes towards the

soundscape. For this study, we wanted to test a broader scale that incorporates a positive,

45

well understood attitude towards sound, referred to as pleasantness (Schomer et al., 2013)

which has been found to be an important indicator in measuring the rural soundscape (De

Coensel & Botteldooren, 2007). A review of factors related to soundscape analysis

determined pleasantness to be a commonly used and significant factor in measuring

soundscape loudness (De Coensel & Botteldooren, 2007). In the current study,

pleasantness was measured on a six-point scale from very unpleasant (1) to very pleasant

(6).

Noise Sensitivity Scale- A shortened field version of the Noise Sensitivity Scale

(NSS) was used to measure individuals’ unique perception of unwanted sounds (Benfield,

Nurse, et al., 2014). The way in which humans react to different sound stimuli is variable.

The purpose of using this measure is to better understand an individuals’ perceptions of

sounds. An example of individual difference in sound perception was found in military

veterans and their response to the loud explosive sounds associated with New Year’s eve,

which elicit a response similar to sounds heard in combat (Chemtob, Roitblat, Hamada,

Carlson, & Twentyman, 1988). Within the context of measuring sound impacts in parks,

NSS has been highly correlated with motivations and acceptability of sounds (Benfield et

al., 2014). The score from the NSS was calculated after reverse coding one of the items,

“I get used to most noises without much difficulty”, to create an overall noise sensitivity

score for each respondent. Values ranged between 2.8 and 6, where lower values indicate

low sensitivity and higher values indicate increased sensitivity to noise.

Ability to hear natural sounds - This measure was developed by the research

team to investigate respondents’ self-report of how often natural sounds were masked by

anthropogenic sounds. For analysis purposes the responses were coded numerically with

46

one being “almost always clearly without interference from human-made sound” and five

being “almost always with interference from human-made sounds”. The higher the value,

the more interference from human-made sounds the respondent reported experiencing.

Spatial Data

Average daytime sound level data for the United States as described by (Mennitt

et al, 2013) was obtained from the National Park Service. In summary, sound data was

collected over 25 days or longer from 319 sites within NP boundaries and 28 cities; for

areas that were not measured, 109 unique variables were used to predict sound levels at

those locations. Variables included climate, population density, land use, land cover,

distance from railways, airports and roads, etc. Sound pressure levels are shown as A-

weighted L50 dBA (Mennitt et al, 2013) which captures sound pressure levels based on

human hearing, and L50 represents the median sound pressure level (or the sound pressure

level present at least 50% of the time) (Austin Noise, 2009).

Zip code boundaries were obtained from the United State Census data in 2015.

All analyses were performed using ArcMap 10.4 (ESRI, 2011).

Analysis of visitors and their home sound environments

To estimate visitors’ average sound level exposure by zip code, the “zonal

statistics by table” tool was used to create output tables. The first step in this process was

creating a data table that only contained data from zip codes that matched the zip code

boundary shapefile. Initially we had zip code data from 441 survey respondents, 372 zip

codes matched with the boundary shapefile. It’s likely that some of the zip codes had

been entered incorrectly by the survey administrator and that the boundary map didn’t

contain all the potential zip codes within the United States. After a shapefile was created

47

that only contained zip code data from respondents that matched with the boundary

shapefile, the “zonal statistics by table” tool was used for each of the raster data files.

These tables were then exported and added to the existing SPSS data files containing

survey responses.

Soundscape of MUWO

Currently no map exists that captures the potential soundscape of MUWO. To

capture the different soundscapes that visitors were exposed to throughout the park a

soundscape of the park was created to capture geophony, biophony and anthrophony

(Figure 2-5). A 1000 ft. buffer around nearby highways and a 500 ft. buffer around park

roads estimates the impact of noise created by vehicle transportation. Buffer distances

were estimated based on a study that modeled noise impacts in protected areas (Barber et

al., 2011). The sound impacts from park streams were estimated by using a 100 ft.

buffer. Noise from visitors on the trail were estimated by creating a 20 ft. buffer on

hiking trails.

48

Figure 2-5. Estimated soundscapes in MUWO

Analysis of the perception of the soundscape

Multiple linear regression tests were performed in SPSS to analyze the potential

relationships between mean sound levels and soundscape perception variables.

Respondents’ rating of the pleasantness of the soundscape was used as the dependent

variable while the mean daytime sound level of home zip code, noise sensitivity, and

ability to hear natural sounds were treated as independent variables. N=372.

49

Results

During May 2016, we collected 537 surveys with a total response rate of 55%.

This response rate is low for intercept surveys in National Parks, but it is similar to other

studies that have been conducted in Muir Woods (Marin et al., 2011; Stack et al., 2011).

Within the sample, 441 respondents reported a zip code within the United States, 83 of

those identified themselves as international. Of the 441 zip codes that were provided, 372

(n=372) matched with zip codes analyzed using the 2015 Census dataset (Figure 4). For

this study, only survey data related to the 372 matched survey participants were analyzed.

Visitors came from 46 different states. The majority of visitors in our sample came from

California (30%). Twelve percent of the population were from nearby large urban areas

such as San Francisco or Oakland. Moreover, a significant portion of the sample reported

being from an urban area (77%), while the other 23% were from rural locations. Almost

half of the sample (48%) reported living 4,000 miles or more from the park and 20% of

the sample live 100 miles or less from the park. Only 6 respondents lived 10 miles or less

from MUWO.

Figure 2-6 shows the distribution of respondents and the average daytime sound

level across the contiguous United States. The minimum mean sound level of

respondents’ zip codes was 30.96 dBA and the maximum mean was 57.03 dBA. On

average, the mean sound level for respondents’ zip codes was 46.86 dBA (Figure 2-7).

Motivations for visiting Muir Woods ranged from “experiencing wildlife in

nature” to “seeing the redwoods” (ranked as the top motivation with an average rating of

5.58 out of 6). The third most important motivation for visiting the park was “to enjoy the

50

natural quiet and sounds of nature”, with an average rating of 5.07. For most of the

sample, hearing quiet and sounds of nature were very important to their visit.

Figure 2-6. Predicted daytime sound level and distribution of visitors’ home sound level exposure

Figure 2-7. Distribution of sound level exposure

12%

63%

24%

Low (<39 dBA) Medium (40-49 dBA) High (50 + dBA)

Visitors Sound Level Exposure

51

Perception of MUWO soundscape

Multiple regression models were analyzed with results from the average daytime

sound level, average nighttime sound level, average natural sounds, and average

anthropogenic sounds. The most parsimonious model used the average daytime sound

level raster data and are presented in this section. Table 2-2 shows results from the

correlation and regression analysis for the relationships of the independent variables

(average daytime sound level based on zip code, noise sensitivity and ability to hear

natural sounds) on the dependent variable, pleasantness of the soundscape (n=372).

Table 2-2 Multiple regression results for pleasantness

Independent variables

Bivariate

Correlati

ons

b-

values Beta

Partial

Correlations

Part

Correlations

Mean Sound Level -.110* -.020* -

.101 -.112 -.100

Noise Sensitivity -.132** -.130** -

.132 -.147 -.131

Ability to Hear Natural

Sound -.439***

.413**

*

-

.430 -.436 -.429

Constant 7.686

Multiple R .466***

Adjusted R-Square .217

* Significant .05 (2-tailed)

** Significant .01 (2-tailed)

*** Significant .001 (2-tailed)

Score based 5 items: 1=low sensitivity, 6=extreme sensitivity

Scale: 1=clearly without interference from human made sounds, 6=always with

interference from human made sounds.

52

Results from a correlation analysis show significant negative correlational

relationships between the independent variables and the dependent variable. The overall

regression model is significant (p<.001). Approximately 22% of the variation in visitors’

perception of the pleasantness of the soundscape is explained by the combined linear

effects of mean average daytime sound level (DTL) by zip code, noise sensitivity, and the

ability to hear natural sounds in the park. Because ability to hear natural sound has the

largest beta coefficient, we can conclude that it has a strongest net relationship with

pleasantness of the soundscape.

Discussion


National Monument?

Findings from this study suggest that a combination of different factors influence

visitors’ perception of the pleasantness of the soundscape in a park context. Results from

the survey revealed the sample population was highly motivated to enjoy the natural quiet

and sounds of nature. According to Schomer et al. (2013) individual perception of the

soundscape is a combination of hearing the physical sound and cognitive assimilation.

Results from this study show factors related to soundscape perception include: the ability

to hear natural sounds during the park visit, sensitivity to noise, and the average sound

level of the respondents’ home zip code. Several studies have explored factors that

influence perceptions of soundscapes (Axelsson et al., 2010; Benfield, Nurse, et al., 2014;

53

Cottrell & Meisel, 2003; De Coensel & Botteldooren, 2007; Marin et al., 2011; Schomer

et al., 2013). A previous study found that motivations can influence visitors’ perceptions

of the soundscape (Marin et al., 2011).

Ability to hear natural sounds was the strongest predictor in the model. According

to results from the bivariate correlations this was a negative relationship, so as the

interference with natural sounds increased, the perception of soundscape pleasantness

decreased. Based on previous measures of the MWUO soundscape, visitors talking is the

most prevalent anthropogenic sound and has the potential to mask natural sounds (Stack

et al., 2011). In a lab study, Benfield et al. (2010) found recordings of voices to have a

significant effect on participants’ ratings of national park scenes. Additionally, the

increased volume of voice sounds negatively affected emotional ratings such as

annoyance, tranquility, freedom, naturalness, and so on. A number of studies have

focused on the influence of motorized sounds in relation to soundscape experience(Mace,

Bell, & Loomis, 2004; Mace, Corser, Zitting, & Denison, 2013; Weinzimmer et al.,

2014), but findings from the current study along with others, highlight the impact of

voices on negative soundscape experiences.

Based on the regression model results, noise sensitivity was a significant predictor

of soundscape pleasantness. Noise sensitivity relates to sound annoyance and habituation

to noise (reviewed in Benfield et al., 2014). Bivariate correlation results showed a

negative relationship; indicating that those who were more sensitive to noise, found the

soundscape to be less pleasant. These findings are similar to another study that tested the

relationship between noise sensitivity and soundscape perception in a national park.

Benfield et al (2014) found that visitors to Rocky Mountain National Park with higher

54

ratings of noise sensitivity to rate aircraft noise as less acceptable and to rate other man-

made noises as more problematic.

Ability to hear natural sounds and noise sensitivity were factors that related to

individuals’ experience with sound in the park and their personal attenuation to noise.

The variable that measured the average of individuals’ home sound level were objective

measures based on raster data estimating sound levels across the United States. These

findings convey the notion that one’s day to day exposure to sound impacts their

perception of sound during a park experience. Schomer et al. (2013) discussed the role of

community context in soundscape perception. According to their paper, community-wide

context includes elements and norms that are different based on type—urban, suburban,

and rural. For example, common urban sounds like emergency sirens and beeping horns

might be considered normal for a resident living in a large city center, but very unfamiliar

in a rural farm community. Ultimately, when visitors’ leave their home environments to

visit parks, their perception of the park soundscape is impacted by the sound level of their

community.



Perception of the soundscape is influenced by more than just the physical

measure of sound (Benfield et al., 2014). Thus, it’s important to explore individuals’

characteristics that effect soundscape judgments. Within the environmental noise

literature, it has been concluded that people in different communities perceive identical

sounds to be either less annoying or more annoying based on their personal norms and

attitudes (Schomer et al., 2013). Different from other research outcomes, this study

55

identified a factor beyond attitudes and norms. To the author’s knowledge, this is the first

study of its kind to explore the relationship between the sound level of individuals’ home

zip code and their perception of park soundscapes. However, this is not the first study to

use sound level of zip code blocks to inform a relationship. Andrew et al. (2013) used

aircraft noise contours paired with zip code blocks, to estimate the correlation between

cardiovascular disease in older adults who live near airports.

Our findings suggest the sound level of individuals’ home sound level contributes

to visitors’ perception of the pleasantness of the parks’ soundscape. The multiple

regression model revealed a negative relationship; meaning that as mean sound level of

zip code increased, the rating of soundscape pleasantness decreased. This finding is not

intuitive, one would guess that as sound level of one’s home zip code increases, they

might find the park soundscape to be more pleasant. A previous study found that as

visitation to MUWO increased, so did sound level (Stack et al., 2011). We postulate that

visitors from louder zip codes might have found the soundscape less pleasant because of

increased sound levels due to noise from other visitors.

Results from our spatial analysis also show that a majority of the sample were

from urban areas. In one study, street-level sound level measurements were taken across

New York City to understand sound exposure in an urban community (McAlexander,

Gershon, & Neitzel, 2015). Most locations measured average sound levels above 70 dBA,

which can be detrimental to health and wellbeing. Results from the multiple regression

model demonstrate the impact of individuals’ day to day soundscape experience on

soundscape perception. Parks and protected areas provide individuals’ experiencing

elevated sound levels in their home environment a place of escape.

56

Management Implications

Management of natural soundscapes in protected areas is important for conserving

wildlife, but also providing visitors with holistic benefits. This research demonstrates

how various factors influence the perception of soundscape pleasantness or health.

MUWO designates certain areas of the park as “quiet zones” and empirical evidence

shows that this method is successful in quieting the park (Stack et al., 2011). It’s

important for other parks, especially those close to urban centers, to adopt similar

management techniques. While parks might be quieter than a busy downtown area, it’s

important to keep these protected places quiet, so that visitors have the opportunity

benefit from the ecosystem services they provide.

National Park units across the country are taking steps to implement plans and

policies that protect natural soundscapes. Findings from this study suggest that perhaps

other agencies should begin to develop plans to protect natural sounds and quiet. In a

study of perceived restoration experiences in urban parks, Payne (2008) found that

visitors’ perception of the soundscape plays a significant role in their restorative

experience. Urban parks that can provide experiences that improve the wellbeing of

urbanites should begin to protect natural sound. This can be done by creating zones that

ask visitors to keep quiet, avoid cell phone use, and mute music.

Limitations and future research

Caution should be taken with these results. Sound level of respondents’ zip code

was predicted based on geospatial modeling data supplied by the National Park Service.

This modeling data is likely to contain errors (Mennitt & Fristrup, 2016). For instance,

the model could potentially overestimate or underestimate sound levels in certain areas.

57

Additionally, respondents’ zip code boundary might not represent the sound level they

are exposed to during the majority of the day. It’s likely that individuals live and work in

different zip code boundaries. Thus, their home zip code might not be the most accurate

variable for estimating typical sound exposure.

Our study suggests that individual exposure to sound can impact perceptions of

the park soundscape. However, our study fails to tease out the relationship between noise

sensitivity and the sound level associated with one’s home zip code. Do people choose to

live in rural or quieter areas because they are sensitive to noise? Understanding these

relationships would also help researchers to better understand the connection between

sound level and housing values. Farmer et al. (2013) found that neighborhoods with

higher levels of bird diversity also had higher housing values. Perhaps those who are

sensitive to noise are willing to pay more to live in a quieter area, thus gaining more

opportunities for natural sound exposure. Future research is needed to understand

individual perceptions of soundscapes.

Conclusion

A previous study estimated that 145.5 million Americans experience sound levels

that exceed those recommended to protect public health (Hammer et al., 2014). This

further justifies the importance for protecting parks and spaces where people can

experience the benefits of sounds of nature. Results from this study show that multiple

factors, including the sound level of individuals’ home zip code, influence their

perceptions of soundscapes. This study was successful in determining the relationship

58

between the level of sound one experiences on a daily basis and perceptions of sound.

Professionals can use evidence from this study to inform future research and management

related to natural sounds and the ecosystem services or benefits they provide to human

health and wellbeing

References
















2846. https://doi.org/10.1121/1.3493436

59










1295. https://doi.org/10.1007/s10980-011-9646-7




https://doi.org/10.1177/0013916512454430



https://doi.org/10.1089/eco.2014.0028







60





https://doi.org/10.1080/01490400701756436



















61


https://doi.org/10.1037/0003-066X.35.3.231



252–262.











https://doi.org/10.1121/1.417102



11(6), 305–313. https://doi.org/10.1890/120183





62



4), 349–362. https://doi.org/10.1080/01490400290050790



349–362. https://doi.org/10.1080/01490400290050790





Association.







283–295. https://doi.org/10.1080/01490400290050745

Holden, L. J., & Mercer, T. (2014). Nature in the learning environment: Exploring the

relationship between nature, memory, and mood. Ecopsychology, 6(4), 234-240.




63


24(3), 369–381.



https://doi.org/10.1016/0272-4944(95)90001-2



https://doi.org/02724944/95/030169+14§12.00/0





Review of Research.











64






242. https://doi.org/10.1080/089419299279713




Manning, R. (2001). Programs That Work Visitor Experience and Resource Protection: A

Framework for Managing the Carrying Capacity of National Parks. Joumal of Park

and Recreation Administration, 19(1), 93–108.



36(4), 557–579.




https://doi.org/10.1080/01490400.2011.550224




https://doi.org/10.1186/s12940-015-0006-y

65











6(3), 257–265. https://doi.org/10.1111/2041-210X.12330





https://doi.org/10.3397/1.599294



Muir, J. (2011). Wilderness essays. Gibbs Smith.



https://doi.org/10.1007/s13398-014-0173-7.2


66











121.













67

9224-1






https://doi.org/10.1121/1.4929934











https://doi.org/10.1080/01490400.2011.564924



https://doi.org/10.1080/01441640902827623



68










https://doi.org/10.1177/0013164404264117



Smith, J. W., & Pijanowski, B. C. (2014). Human and policy dimensions of soundscape

ecology. Global environmental change, 28, 63-74.




https://doi.org/10.1121/1.3531803






69





Resources, 8(4), 351–30.




Thoreau, H. D. (1854). Economy. Walden, ch, 1.



https://doi.org/10.3390/su9112088

Vaske, J. J., & Donnelly, M. P. (2002). Visitor Crowding and Normative Tolerances at

Congested Areas of Rocky Mountain National Park Xinran Lehto Assistant

Professor Department of Natural Resource Recreation and Tourism Human

Dimensions in Natural Resources Unit Colorado State University, (May).


Human Responses to Simulated Motorized Noise in National Parks. Leisure

Sciences, 36(February 2015), 251–267.

https://doi.org/10.1080/01490400.2014.888022

Wilson, E. O. (2001). Nature matters. American Journal of Preventive Medicine, 20(3),

241–242. https://doi.org/10.1016/S0749-3797(00)00318-4

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Chapter 3 Aircraft Sound Management in Denali National Park and Preserve



Q1: How can researchers best inform the development of thresholds for soundscape

quality using dose response methodology?

Q2: What factors influence visitors’ perception of overflight audio clips?

Abstract: Viewing vast landscapes by flight is popular in places like the Grand Canyon, Hawaii

Volcanoes, and Denali National Park and Preserve. Park managers are responsible for planning

and monitoring multiple resources of parks, including the soundscape or acoustical environment

and visitor experience. Therefore, it is important for parks that are viewed by air tours to measure

the impact of aircraft overflight noise on visitor experience. A common method for measuring

visitor response to sound is through a method called dose response. This study used an

innovative, dose response methodology to measure visitor response to aircraft noise in Denali

National Park and Preserve’s frontcountry or more developed area of the park. In previous

studies, audio clips have been used to measure visitors’ reaction to sounds, this study was unique

in that audio clips were played in a random order and potential thresholds were explored using

linear regression. Each respondent listened to 5 randomly chosen audio clips of propeller aircraft

from a suite of 36 clips at varying sound levels. Response to audio clips were predicted using

general mixed linear models. Results show that sound level is an important variable in response to

noise. Additionally, these models help inform thresholds for sound level and the number of

overflights deemed acceptable by visitors.

72

Introduction

Denali National Park and Preserve, located in south-central Alaska, is comprised of more

than six million acres of scenic mountains, glaciers, rivers, and forest. Given the vast size of the

park, most visitors only see a small portion of the park during their visit. Like other destinations

in the National Park system, such as the Grand Canyon and Hawaii Volcanoes, viewing the park

by air allows for a bird’s eye view of these expansive landscapes. Unlike high altitude

commercial flights, air tours operate at lower elevations with different types of engines and flight

patterns, thus influencing sound propagation differently. Over 100 national parks are viewed by

air tours and subsequently, visitors on the ground are exposed to aircraft sound (Miller, 2008).

Aircraft overflight noise in parks and protected areas have been shown to impact both wildlife

(Pepper, Nascarella, & Kendall, 2003) and visitors (Benfield et al., 2014; Mace, Bell, & Loomis,

1999; Miller, 1999; Taff et al., 2014). As commercial flightseeing tours gain popularity, park

managers need to understand the impacts of the anthropogenic sounds produced by overflights on

visitor experience.

Noise, defined as an unwanted sound, produced by aircraft overflights have long been

studied in residential areas impacted by airport traffic (Reviewed in Rapoza, Sudderth, & Lewis,

2015). In the community noise context, residents are exposed to air traffic on a more consistent

basis, when compared to park visitors who experience isolated events. Residential studies have

found air traffic noise to impede human cognition, induce stress, and impact other measures of

health (Babisch, 2003; Cohen et al., 1980). Studies that focus on aircraft noise in the park context

aim to better understand the impact of noise on park experiences. Mace et al. (1999) conducted a

laboratory simulation of a park experience and found that aircraft noise at both high and low

levels impacted respondents’ ratings of scenic beauty, naturalness, and solitude. As noise levels

increased, so did annoyance. In a follow up to this study Mace, Bell, Loomis, and Haas (2003),

used similar methods to test the influence of natural sounds paired with aircraft noise on factors

73

related to park experiences. They found similar results to Mace et al. (1999), in that increasing

noise negatively impacts park experiences. Benfield et al. (2010) expanded this research even

further and tested the influence of other anthropogenic park sounds on human response. Ground

traffic, voices, and aircraft were compared in terms of their impact on park visitor experience.

Results from this study found aircraft noise to have a negative influence on ratings of scenic

beauty. In other words, noise from aircraft decreased measures of scenic beauty.

Increased noise levels are a growing concern for national parks because as visitation

increases, so does unwanted sounds from transportation (National Park Service, 2006). A recent

study found that anthropogenic noise nearly doubles background sound levels in the majority

(63%) of protected areas in the contiguous United States (Buxton et al., 2017). Several methods

for measuring the impact of noise on park visitor experience have been used (Benfield, Nurse, et

al., 2014; Pilcher, Newman, & Manning, 2009; Stack et al., 2011; Taff et al., 2014; Weinzimmer

et al., 2014). As mentioned earlier, researchers have utilized university laboratory space to

simulate national park experiences. Other studies have used a dose response methodology to

simultaneously measure park sound and visitor response to specific sounds (Anderson, Rapoza,

Fleming, & Miller, 2011; Fidell et al., 1996; Miller, 1999). Commonly the goals of these studies

are to determine a threshold, or point at which aircraft sounds are no longer deemed acceptable.

The purpose of this paper is twofold. First, to build on and improve methods for measuring visitor

response to noise that inform thresholds for soundscape quality. The second purpose is to

understand the factors that influence visitor response to aircraft sound.

Literature Review

Protecting Natural Sound in Parks

People who visit national park sites have a number of different important reasons or

motivations for their visit. Escaping noise ranks as one of the top most important reasons visitors

use parks and protected areas (Driver, Nash, and Haas 1987). In one study that surveyed visitors

74

at 39 national park sites across the country, 91% of visitors rated “enjoying natural quiet” as an

important reason for their visit (McDonald et al, 1994). In the same study, 93% of visitors also

rated “viewing natural scenery” as an important reason for their visit, meaning that hearing nature

is just as important as viewing it. Results from these and other studies further justify the

significance of protecting natural sounds for future generations, the main mission of the park

service.

Over the past few decades, the growing concern related to park noise has centered on

aircraft overflights. Grand Canyon National Park gained the most attention due to the growing

popularity of helicopter sight-seeing tours (Reviewed in Mace et al., 2013). Horonjeff et al.

(1993) measured the impact of aircraft noise at the Grand Canyon and found that noise from loud

helicopters to be audible during the majority of the day. In 1987 Congress passed the National

Parks Overflight Act, which required park units to analyze overflight impacts and restore natural

quiet (NPS, 1987). After the 1987 mandate, Congress went on to further direct protection of

natural sounds with Air Tour Management Plans (ATMPs) (NPS, 2000). The purpose of ATMPs

is to prevent noise from commercial air tour operations from negatively impacting park resources

or visitor experiences.

Several studies have demonstrated the adverse effects of hearing aircraft noise in parks.

For example, Tarrant, Hass, and Manfredo (1995) evaluated the effects of overflights on visitors

to wilderness areas in Wyoming. Respondents that were exposed to noise from aircraft reported

lower levels of solitude and tranquility, important characteristics of the wilderness experience.

Other studies have found that aircraft noise can depreciate memory (Benfield et al., 2010),

cognitive function ( Abbott, Newman, Taff Benfield, & Mowen 2015), and landscape

assessments (Weinzimmer et al., 2014). When the effects of aircraft noise are measured at the

community level, it has been found to adversely affect cognitive ability and stress (Haines et al.,

2001).

75

Methods used to assess the soundscape vary, but generally audio recording devices are

deployed and sound sources, levels, and frequencies are measured. A common method for

measuring impacts of overflights on visitor experience is through dose response (Anderson et al.,

2011; W. A. Freimund, Vaske, Donnelly, & Miller, 2002; Nicholas P. Miller, 2008; Rapoza et al.,

2015). These studies have included both in-situ dose measures where the park soundscape is

measured in congruence with visitor response to sounds (Anderson et al., 2011), as well as,

simulated where aircraft sounds are played through audio clips (Rapoza et al., 2015).

Dose Response Methods

The dose response method measures the level of sound a participant is exposed to while

simultaneously asking the participant to evaluate their response to varying sound attributes (Fidell

et al, 1996). This methodology has been commonly used to measure human response to sounds in

community noise assessments. For example, Pedersen and Waye (2004) examined residents’

response to wind turbine noise. The NPS also uses this methodology to understand park visitors’

response to both natural and anthropogenic sounds (Anderson et al., 2011; Miller, 1999; Rapoza

et al., 2015). Rapoza et al. (2015) measured noise exposure and visitor response to aircraft noise

in several backcountry national park sites. In other studies, the dose response variable was

estimated by visitors through survey questions. Tarrant, Hass, and Manfredo (1995) asked survey

respondents if they heard aircraft sounds and how often those sounds were audible. Researchers

concluded that respondents had strong negative attitudes towards hearing overflights and were

slightly more affected by hearing overflights than seeing them. Fidell et al. (1996) used both on-

site and telephone surveys to measure the relationship between aircraft noise and annoyance in

wilderness areas. Studies that measure both the physical soundscape and response have been used

to inform reasonable limits for aircraft sound that can aid in park management (Miller, 1999;

Rapoza et al., 2015).

76

Studies have utilized both the field and laboratory for analyzing human responses to

sound through dose response methodology. Anderson et al. (2011) calculated dose response

variables for aircraft overflights and matched physical measurements of sound with visitor

surveys at several national parks. In these studies, microphones are deployed in the field and are

used to measure the soundscape visitors are exposed to. From microphone recordings, various

variables related to the physical soundscape can be determined. These can include sound source,

sound level, and percent time sources are audible. Aasvang and Engdahl (2004) utilized field and

laboratory observations to measure outdoor recreationists’ response to aircraft noise near the main

airport in Oslo, Norway. They found that subjects responded similarly to field and lab overflight

noise exposures.

The laboratory setting provides a more controlled measure of dose response than the

field. In most cases, study participants are exposed to audio recordings of soundscapes that aim to

recreate a park experience (Mace et al., 1999, 2013; Weinzimmer et al., 2014). Mace and others

(1999) aimed to simulate a Grand Canyon soundscapes experience where participants were

exposed to high and low levels of helicopter noise. Results from this study found that helicopter

noise interfered with variables related to positive visitor experiences, including the visual

aesthetic quality of landscapes. Weinzimmer et al. (2014), tested human response to a series of

different natural and motorized sounds heard in national parks including: natural sounds,

propeller planes, motorcycles, and snowmobiles. This study also simulated a park experience and

found that all motorized sounds resulted in negative evaluations of landscape quality. While

laboratory settings allow for more control of the specific sound dose and potential confounding

factors, field studies that utilize recorded audio clips sample a realistic group of visitors and don’t

need to suggest a park experience.

Asking survey respondents at a national park to listen and respond to audio clips allows

for more control of the soundscape without having to simulate an already “realistic” park

77

experience. Several studies have used this dose response method in the field to understand park

visitors’ response to specific anthropogenic sounds (Marin et al., 2011; E. J. Pilcher et al., 2009;

Taff et al., 2014). For example, Pilcher et al. (2009) used a two-phase study that included in-situ

and audio clip dose response methods to inform soundscape management at Muir Woods

National Monument. Survey respondents were intercepted during their park visit and asked to

listen to sound clips of varying levels of human-caused sound. In another study, Marin et al.

(2011), used dose response methods in the field to understand the role of motivation to hear

natural sound in acceptability of both natural and human-caused sound. This study would have

most likely had a different outcome if it was field based vs. lab based; as park visitors likely have

defined motivations whereas lab participants do not.

Indicators and Thresholds for Soundscape Quality

This study design was developed based on previous research that measured indicators and

thresholds for soundscape quality in national parks (Freimund, Vaske, Donnelly, & Miller, 2002;

Marin et al., 2011; Pilcher et al., 2009). Indicators and thresholds of quality have been used to

guide and develop park management plans and policies (Manning, 2011). They are an integral

part of empirically measuring park carrying capacity for various frameworks including: Limits of

Acceptable Change (Stankey, Cole, Lucas, Petersen, & Frissell, 1984), Visitor Impact

Management (Kuss, Graefe, Alan, & Vaske, 1990), and Visitor Experience and Resource

Protections (National Park Service, 1997; Manning, 2001). An indicator is a measurable variable

based on an identified management goal. These variables can be biophysical, such as

environmental impacts, or social/experiential, such as crowding. Indicators vary depending on

specific management objectives, like whether or not an area is managed for a frontcountry or

wilderness experience. Threshold is defined as the minimum acceptable level of indicator

variables. For example, if crowding and the number of people on a given trail are identified as an

78

indicator; the threshold would represent the minimum number of people on the trail that are rated

as acceptable.

Various methods are used to identify indicators and thresholds. Potential indicators can

be determined by interviewing visitors and/or managers, as well as, through surveys with closed

and open-ended questions (Manning, 2011). Normative theory has been a common empirical

approach to informing park thresholds for quality (Manning, 2011; Shelby, Vaske, & Donnelly,

1996; Vaske & Donnelly, 2002). “Norms” can be defined as behaviors that groups or individuals

consider to be “normal” (Manning, 2011). This is usually based on an individual, societal, or

cultural idea. Norms are more powerful than attitudes because they define how people should

behave (Manning, 2011). In this approach, indicator variables are first identified. Thresholds can

be determined or informed by a social normative curve, where acceptability of a park resource or

impact are evaluated. Average ratings of acceptability are plotted with acceptability on the

vertical axis and the resource indicator on the horizontal axis. The point where the level of

acceptability drops below the middle point is considered the minimum level of acceptability. The

value associated with this point is used by park management to inform visitor thresholds for

resource impacts (IVUMC, 2016).

Within the context of soundscapes, Pilcher at al. (2009), conducted a two-phase study to

measure indicators and thresholds to inform soundscape management at Muir Woods National

Monument. In the first phase of the study indicators of soundscape quality were identified

through an in-situ dose response method. Survey respondents rated the sounds they heard during

an attended listening exercise on a scale from pleasing to annoying. Sounds that were heard by a

majority of respondents and rated on average as annoying were determined to be good indicators

of soundscape quality. Noise from groups of visitors talking were identified as a potential

indicator. In phase-two of the study, a threshold for visitor talking noise was determined by using

audio clips. Respondents listened to a series of varying sound levels (dB) of visitor noise and

79

rated the acceptability of each clip. On average, respondents rated visitor talking noise above 38

dB as unacceptable. These results aided in informing a threshold for sound quality, and

subsequently, permanent interpretive signage encouraging visitors to be quieter in certain areas of

Muir Woods (Stack et al., 2011).

There are critiques of the normative approach to informing thresholds. First, with more

complex indicators of quality, such as ecological impacts or crowding, visitors might find it

difficult to determine a minimum acceptable number of people of level of impact (Manning,

2011). As a result, visual approaches have been used in a number of studies to measure a range of

crowding scenarios or resource impacts (Heywood, Murdock, Heywood, & Murdock, 2002;

Inglis, Johnson, & Ponte, 1999; Manning & Freimund, 2004). Researchers use pictures of varying

levels of impact to aid respondents in determining acceptable levels. Visual, as well as, auditory

approaches to empirically informing thresholds provide visitors with a more detailed and realistic

way of rating the acceptability of resource conditions; whereas narratives could be awkward and

difficult to understand. Another consideration of these methods is the order in which pictures or

audio clips are presented. For example, in Marin et al. (2011)’s study, audio clips were played for

survey respondents in increasing order, which could have impacted their acceptability rating. The

paper suggests playing clips in a random order so that listeners focus on single recordings and

less on the rating of the previous recording.

More recently, the bias associated with the presentation of photos has been explored,

specifically range and order effect (Gibson, 2011). Most studies present 6-8 photos of increasing

levels of impact and on average, visitor ratings of acceptability drop below zero after the fourth

photo. To understand if the order of photos presented to respondents introduced bias, linear

models were used to test the impact of presentation range and order on acceptability of photos.

Results suggested that the order and sequence of photos did influence respondents’ evaluation.

80

Recommendations from these findings suggest using pseudo-random order in presenting survey

respondents with varying levels of resource impact.

Study Purpose

In summary, earlier studies have used dose response methodology to measure national

park visitors’ response to noise in both field and laboratory settings. While lab studies allow for

more control in soundscape experience, laboratory samples are made up of undergraduate

students that don’t accurately represent the motivations and expected experiences of park visitors.

Dose response has also been used to inform the development of indicators and thresholds for

soundscape quality in national parks. However, there are some issues with previously developed

methods. Playing audio clips for respondents in the field allows for a more controlled dose, but

the order in which clips are administered needs to be considered. In Pilcher et al. (2009), audio

clips were played in ascending order. This might have impacted the way in which visitors rated

audio clips. Additionally, Gibson (2011) found that order and sequence of the presentation of

photos biased respondents ratings of acceptability. Therefore, the purpose of this paper is to apply

an innovative methodological approach to informing park thresholds for soundscape quality that

improves the validity of study findings. This study used pre-developed audio clip dose response

methods that allowed for more control and drew from a varied sample of park visitors. We also

utilized a large suite of varying audio clips in a randomized order, which aims to eliminate the

bias potentially associated with clip order, limited sound ranges, and sequence effects.

Methods

Survey Location

Denali National Park and Preserve (DENA) is located in south central Alaska, north of

Anchorage and south of Fairbanks. The park is comprised of six million acres of wildland and a

single access road (NPS, 2017). Travelers come to DENA to view wildlife, hike through alpine

tundra, and either view or climb North America’s tallest peak, Mt. Denali. A substantial amount

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of frontcountry activities take place near the facilities encompassing the Denali Visitor Center

campus. This includes hiking developed frontcountry trails, visiting the Denali Visitor Center,

camping and picnicking, and attending educational programs. These facilities are within close

proximity to anthropogenic sound sources, including an aircraft landing strip, roads, and a train

depot which are sources of potentially unwanted sounds heard by visitors. For this study, visitors

were intercepted at four different survey locations, which allowed for us to sample different types

of frontcountry users (day-use, overnight campers, etc.).

In 2014 DENA completed a report that informed indicators and thresholds of soundscape

quality for backcountry locations (i.e., locations within designated wilderness, managed for

wilderness experiences) (Newman et al., 2014). Data collection for this report spanned several

summers and included in-situ audio clip dose response methods and a listening exercise. The first

phase of this report utilized a listening exercise where respondents reported the sounds they heard

during the three-minute exercise and rated their response to each sound. These data determined

that aircraft overflight noise was an indicator of quality for all backcountry locations. In a second

phase of the study, audio clips were used to inform thresholds for aircraft overflights from three

sources: propeller aircraft, jets, and helicopters. Results from the 2014 report were used in

developing methods for the current study. First, dose response survey methods were replicated for

future comparison between backcountry and frontcountry users. Second, results from the report

helped to identify potential indicators of quality for frontcountry users (e.g. respondents that are

intercepted while using the more developed, frontcountry area of DENA). One of the survey

administration sites in the report, the Triple Lakes Trail, was located near the Denali Visitor

Center Campus. Results from an in-situ listening survey conducted at this location found noise

from aircraft to be an indicator of quality (Newman et al., 2014).

Results from this current study are part of a larger, comprehensive technical report that

measured the current state of soundscapes and their impact on visitors to DENA’s frontcountry.

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Park managers are seeking empirical evidence to inform research questions about the impact of

aircraft overflight noise on visitor experiences in the frontcountry. DENA management is

concerned with the number of commercial flightseeing tours within park boundaries, as well as,

aircraft using the landing strip and the impact of the noise associated with air traffic. Commercial

flightseeing tours most commonly use propeller aircraft. Therefore, park managers are interested

in visitor thresholds associated with propeller aircraft. Results from this study and the technical

report will inform indicators and thresholds for DENA to monitor based on management

objectives.

Audio Clip Dose Response Survey

The survey was administered from June 23rd to July 29th, 2017 at four different locations

within Denali’s frontcountry. These locations included: the Denali Visitor Center (DVC),

Horseshoe Lake Trail (HS), Healy Overlook Trail (HO) trails, and the Murie Science and

Learning Center (MSLC). Surveys were collected at the MSLC on days when inclement weather

made sampling at the HO Trail difficult. During the sampling period, trained surveyors used a

random number generator to choose a number between 0 and 30 that represented the time at

which they would intercept their first visitor group that was either entering or exiting the

sampling location. Because of the high volume of visitors at the Denali Visitor Center,

researchers would intercept every 3rd group they encountered. Due to the medium and low

volume of visitors at the Horseshoe Lakes and Healy overlook trails, researchers would intercept

the 1st visitor they encountered after the last survey was complete. Visitors were then asked if

they would participate in a survey. Visitors who were unwilling or unable to participate in the

survey were asked two questions that assessed non-response bias. Visitor groups who agreed to

participate in the survey were then asked who had a birthday closest to the current date. This

method allowed for randomization within groups. The research assistant then handed the visitor a

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laminated (re-usable) copy of the questionnaire and instructed the respondent to provide verbal

responses that were recorded by the surveyor using a tablet computer.

After answering several demographic questions, survey respondents were asked to listen

to a series of five randomly chosen, 30 second sound clips of propeller aircraft. Respondents were

provided noise canceling headphones (BOSE Quietcomfort 15 Headphones) and asked to listen to

all five recordings until completion. After each audio clip was played, respondents rated the clip

on a 9-point acceptability scale and a 9-point interpretation scale (Marin et al., 2011; Taff et al.,

2014). Audio clips were played through the iPad tablet computer and amplified through the JDS

Labs C5D Headphone AMP+DAC. After the five audio clips were played and rated, the survey

administrator then replayed the clip that was rated as the most acceptable or most pleasing (if

more than one sound clip had the highest rating for acceptability or interpretation, the first sound

clip played was chosen). After listening to the final audio clip (sound clip 6) the respondents then

rated the clip for acceptability of times heard per hour and per day.

Audio clip Development

A pool of 36 different audio clips were developed in order to best represent realistic

propeller aircraft overflight events that occur in DENA’s frontcountry. Each audio clip was

overlaid on a single clip of natural sounds such as wind and birdsong. Each clip was 30 seconds

in length, with the overflight lasting approximately 25 seconds, with the natural sounds playing

for the first few seconds and the last few seconds, thus simulating an actual overflight. The 30

second length of audio clips was chosen based on previous research (Rapoza et al., 2015).

Additionally, this study took place in the field, so longer audio clips could have caused

respondent annoyance or survey fatigue. Overflight audio clips were recorded at several sites

located in DENA’s frontcountry, therefore audio clips were representative of actual overflights.

The research team and DENA staff developed a methodology to best randomize the five

different audio clips that respondents rated during the dose response survey. Script written in

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Python was used to generate over 500 options for random audio clip order, with specific

parameters and guidelines. The first audio clip was chosen randomly from the pool of 36 different

audio clips with varying sound pressure levels. Sound pressure level was expressed in decibels

weighted to reflect human hearing (dB(A)). The audio clip played second had to have a least a

six dB(A) difference from the first audio clip. This difference could have been a higher or lower

sound level. The next three audio clips where chosen randomly with the same parameters. Audio

clips average sound levels were between 50.6 and 78.3 dB(A). There were some limitations to

this method and the sequence of audio clips was not perfectly random. Figure 3-1 shows this

discrepancy. A trend emerged where the second and fourth audio clips played were at a lower

sound level. Survey respondents listened to audio clips that were loaded onto an iPad tablet

computer and played through a portable USB amplifier (JDS Labs C5D Headphone amp+DAC)

and noise canceling headphones (BOSE Quietcomfort 15).

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Response measures

Response measures for audio clips were developed based on those previously used in other dose

response studies (Marin et al., 2011; Stack et al., 2011; A. Rapoza et al., 2015). After each audio clip was

played, respondents rated the acceptability and annoyance of the clips on a 9-point Likert scale (i.e. -

4=very unacceptable to +4=very acceptable, and -1=very annoying to +4=very pleasing). The sixth sound

clip was selected from the previous set by determining which overflight the respondent rated as the most

acceptable or the least annoying. After listening to this sound clip for the second time, respondents were

asked to rate the recording in terms of the acceptability of hearing that sound in minutes per hour. This is

a temporal measurement with varying rates, from once every three minutes to once every hour. Finally,

the instrument asked respondents to rate their acceptability of hearing the 6th audio clip at varying levels

of times per day, as well as, their maximum acceptability for hearing overflights in a given day.

Figure 3-1. Summary of survey response for acceptability for varying

sound levels

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Data Analysis

These data were analyzed using a generalized linear mixed model (GLMM) using the

nlme package for R (R Core Development Team 2014). The purpose of this analysis was to

determine what factors, including sound level (dB), might impact visitor response to aircraft

noise. Eight candidate models were hypothesized based on factors that might influence

respondents’ ratings of the audio clips. These fixed effects or factors included: sound level

(LAeq30s); clip sequence; an interaction with sound level and clip sequence; difference in sound

level from the previous clip (LAeq30s); survey site; and roughness. Sound level was measured as

LAeq, which can be defined as the total A-weighted sound energy level measured over a period

of time. A-weighting weighs the sound pressure level based on human hearing (Austin Noise,

2009). The audio clips were 30 seconds long, so the sound energy level is measured based on an

average of those 30 seconds. Sound roughness can be defined as the “buzzing, rattling auditory

sensation accompanying narrow harmonic intervals” (Vassilakis & Kendall, 2010, p.1). The

roughness measure used in this study was based on the median calculation, expressed as Aspers.

Clip sequence refers to the order in which the clips were played for individual respondents.

For all models the individual respondent was chosen as the random effect. This allows

the model to account for individual biases among the respondents. Best models were chosen

using the AICcmodavg package to extract AIC scores and model weights for candidate models

for each of the factors (Shannon, Crooks, Wittemyer, Fristrup, & Angeloni, 2016). AIC model

weights can be interpreted as the probability that the model is the most predictive given the set of

candidate models. When it is unclear which model is the best, model averaging can be used

choose the best model based on the combined influence of specific parameters and effect size

(Burham & Anderson, 2002). Effect sizes were analyzed by whether the 95% confidence interval

(CI) for each factor overlapped zero. If the CI did not overlap zero, the factor was used in the

final model. Four separate models were analyzed as part of this study. These included annoyance

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of audio clips, acceptability, acceptability of overflights in minutes per hour, and acceptability of

overflights per day.

Results

Audio clip listening surveys were collected from June 24th to July 28th, 2017. The survey

yielded an 85% response rate and 489 completed surveys. At the DVC 160 surveys were

completed, 185 at the HL trail, 115 at the HO trail and 24 at the MSLC. For the purpose of this

analysis, the data was aggregated and not analyzed by site. Final models were chosen based on

results from model averaging. Table 3-1 shows final models, along with AIC corrected weights.

AIC weights are all less than zero, meaning that there was a very low probability of these models

being the “best” models. To eliminate the uncertainty related to choosing best models based on

AIC weights, individual factors that had the most overall strength given the candidate models

were analyzed by their effect size. Final models were determined based on the results in Table 3-

2; where factors whose CI did not overlap zero where used in final models.

Table 3-1. Final GLMM models

Model equations AICc weight

acceptability ~ LAeq30s + clip sequence + site + (subject) <0.0

annoyance ~ LAeq30s + clip sequence (subject) <0.0

acceptability (min/hour) ~ LAeq30s + min length + site + (subject) <0.0

acceptability (times/day) ~ LAeq30s + day length + site + (subject) <0.0

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Table 3-2. Observed relationship between each response variable and the model-averaged

parameters from the final models

Response variable Parameter 𝜷 Estimate (95% CI)

Acceptability LAeq30 seconds -0.11 (-0.12/-0.11)

LAeq30second*Clip Sequence 0.0 (-0.01/0.0)

Clip Sequence -0.12 (-0.16/-0.09)

Difference from previous clip 0.01 (0.0/0.02)

Location 0.67 (0.02/1.131)

Median Roughness -0.02 (-0.02/-0.01)

Interpretation LAeq30 seconds -0.09 (-0.09/-0.08)

LAeq30second*Clip Sequence 0.0 (-0.1/0.0)

Clip Sequence -0.09 (-0.12/-0.6)

Difference from previous clip 0.0 (-0.01/0.01)

Location 0.44 (-0.11/0.99)

Median Roughness -0.01 (-0.02/-0.01)

Acceptability (minutes per hour) LAeq30s (Clip 6) -0.03 (-0.05/0.0)

Length (min per hour) -0.13 (-0.14/-0.13)

Location 0.24 (0.05/0.43)

Acceptability (times per day) LAeq30s (Clip 6) -0.01 (-0.03/0.01)

Length (times per day) -0.05 (-0.05/-0.05)

Location 0.19 (0.01/0.36)

*Bold text denotes 𝛽 estimate with 95% CI that do not overlap zero.

Acceptability

The results for all sites combined, using model averaging (Table 4) showed that LAeq,

clip sequence, and location were key explanatory variables. The predicted outcome based on the

final model (Figure 3-2) showed that low levels of noise were rated as acceptable, but as noise

level increases, acceptability decreases. Acceptability varied by site and was determined to be a

contributing factor to the overall model. All three hypothesized variables for acceptability of

aircraft express in minutes per hour were key contributors to the model: LAeq, length (minutes

per hour), and location. The predictive regression model (Figure 3-3) found that hearing aircraft 3

minutes per hour was rated as slightly acceptable at all sound levels. Hearing aircraft for nine

minutes or more per hour was rated as unacceptable at all noise levels. For the acceptability of

times per day, both length (in times per day) and location were key contributors to the final

model. While LAeq did not overlap the 95% CI, it was left in the final model because LAeq is an

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important component of the model outcome. The predictive regression model (Figure 3-4)

showed that hearing aircraft one time per day was acceptable at all noise levels. At 10 times per

day all noise levels were rated as slightly unacceptable or almost neutral. Twenty-five times per

day was rated as unacceptable and 50 to 100 times per day was rated very to extremely

unacceptable at all noise levels.

Figure 3-2. Predicted relationship between visitor acceptability and aircraft noise level using

survey data collected at all sites (MSLC, HL, HO, and MSLC).

Figure 3-3. Predicted acceptability models by number of overflights (3, 9, 15, or 30 minutes per

hour). Solid lines represent the predicted relationship between acceptability and sound level

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Figure 3-4. Predicted acceptability models by number of overflights (1, 10, 25, 50, or 100 times per

day). Solid lines represent the predicted relationship between acceptability and noise level.

Interpretation

For the interpretation response, LAeq and clip sequence were found to be the two key

factors in the hypothesized models. Based on the results from the predicted model, low noise

levels were rated as slightly annoying or neutral, but as noise level increased, annoyance

increased (Figure3-5). Surveys were deployed at four different locations in DENA’s frontcountry.

Location of the survey was not a key factor in predicting annoyance.

Figure 3-5. Predicted relationship between visitor interpretation (pleasing to annoying) and

aircraft noise level using survey data collected at all sites (MSLC, HL, HO, and MSLC).

.

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Numerical Threshold

Respondents were asked follow up questions regarding their response to the 6th audio clip

(the clip rate as the most acceptable/pleasing). Seventy-six percent of respondents indicated that it

would be OK to hear some small aircraft sound as they heard in sound clip six (Table 3-3). Of

those who indicated it would be OK to hear some aircraft sounds, 18% indicated they would

prefer to hear no more than one flight per hour, 27% indicated they would prefer to hear no more

than 2 flights per hour, and 27% indicated they would prefer to hear no more than 3 small aircraft

sounds per hour.

Table 3-3. Acceptability of hearing small aircraft sounds from recording #6 (flights per hour)

Percent of

respondents

Preference of flights per hour

Mean1 Minimum Maximum SD

OK to hear some 76 8.8 1 2000 103.8

Prefer to never hear 24 - - - - 1Median = 3.

Over half of the sample (55%) specified a number of overflights they could hear before they

would no longer visit DENA (Table 3-4). Of the 55% who specified a number of overflights, the

median number was 25 overflights flights per day. Forty-five percent of respondents indicated

that they would visit DENA frontcountry regardless of the number of overflights heard.

Table 3-4. Acceptability of hearing aircraft sounds from recording #6 (times per day) before

respondent would no longer visit Denali

Percent of

respondents

Flights per day

Mean1 Minimum Maximum SD

No more than… 55 45.5 1 1000 74.7

I would visit regardless of

how many aircraft heard 45 - - - -

1Median = 25.

The majority of respondents reported hearing aircraft during their time in DENA (66%).

Table 3-5 shows results from the question, “if you heard aircraft, how bothered, disturbed, or

annoyed were you by other aircraft?” Forty-five percent of the sample reported being not at all

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bothered, disturbed, or annoyed. However, over half (51%) reported being slightly-moderately

bothered, disturbed, or annoyed by other aircraft.

Table 3-5. Respondents bothered, disturbed, or annoyed by other aircraft

Bothered, disturbed, or

annoyed by other

aircraft

Percentage

Mean1 SD Not at all Slightly Moderately Very Extremely

DVC 43 36 18 3 1 1.8 0.9

HL 43 34 18 7 3 1.8 1.0

HO 52 27 14 5 1 1.8 1.0

MSLC 33 27 40 0 0 2.1 0.9

Overall 45 33 18 2 2 1.8 0.9 1Annoyance based on 5-point scale (1 = Not at all; 2 = Slightly; 3 = Moderately; 4 = Very; 5 =

Extremely)

Discussion

The purpose of this study was to explore an innovative method for informing thresholds

for soundscape quality. A dose response method that drew from a pool of 36 varying levels of

propeller aircraft sound was utilized. This chapter will discuss the research findings, managerial

implications, and directions for future research.

Q1: How can researchers best inform the development of thresholds for soundscape quality

using dose response methodology?

Aircraft noise in national parks can be an indicator of soundscape quality therefore

negatively impacting visitor experience. Results from Newman et al. (2014) found aircraft to be

an indicator of soundscape quality near DENA’s frontcountry. Response to the propeller aircraft

sounds heard by respondents were rated on average as ‘annoying’, suggesting its impact on

quality visitor experience. Additionally, results from the current study showed that of the

participants that reported hearing aircraft sounds during their visit to DENA,over half (51%)

reported being slightly-moderately bothered, disturbed, or annoyed by other aircraft. Our study

built on previous dose response methods to inform potential thresholds for propeller aircraft

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sounds (Pilcher et al., 2009; Rapoza et al., 2015). To better control for propeller aircraft exposure,

respondents listened to five audio clips of varying levels of propeller aircraft, chosen randomly

from a suite of 36 clips.

This study was different from others that have utilized audio clips because of the large

suite of varying levels of propeller aircraft sounds that were played in a random order for each

respondent. This randomization technique helped improve the validity of responses to sound.

Pilcher et al, (2009) used five different levels of audio clips in Muir Woods to determine a

soundscape threshold. Audio clips were played in an ascending order, which has been shown

impacted how study participants responded (Gibson et al., 2011). Our study was also unique in

that a wide range of varying audio clips were used. In other studies that use dose response, a

fairly small suite of audio clips are used for comparison (Mace et al., 1999; E. J. Pilcher et al.,

2009). Only 5 audio clips that ranged from 31 to 48 dB were used in Pilcher et al. (2009).

The techniques used to analyze responses to audio clips were also more robust. Pilcher et

al., (2009) used mean ratings of audio clips to determine the point at which the majority of the

sample no longer deemed the sound clips acceptable (i.e. the point at which the average ratings

fall out of the acceptable range and into the unacceptable range). In the current study, general

linear mixed models (GLMM) were used to predict visitor response to varying levels of audio

clips. GLMM regression models are powerful in that they account for the variation or random

effects of independent variables (Burnham & Anderson, 2002). Results from model averaging

showed that random effects of each individual were an important contribution to final models.

Additionally, multi-variate regression analysis allows researchers to better understand which

variables may or may not contribute to respondents’ evaluation of audio clips.

Ultimately, the large suite of varying sound levels in audio clips and robust analysis used

in this study provide a more rigorous and accurate understanding of potential visitor thresholds.

Park managers and researchers that are interested in determining thresholds for soundscape

94

quality should consider adapting this methodology in order to answer complicated research

questions. Sounds are a complex resource that require a more vigorous approach to measuring

and understanding how visitors respond to them.


Results from generalized mixed linear models showed that visitors’ response to sound

depends largely on the loudness of specific noise sources. Sound level (LAeq30s) was an

important factor in all four regression models. This finding was consistent with Pilcher et al.

(2009) who determined that the level of visitor noise impacted visitor dose response in Muir

Woods National Monument. Results from predicted regression models also show that visitors are

annoyed with propeller aircraft noise, even at low sound levels. These findings are in line with

other studies that have found park visitors to report annoyance with aircraft at both low and high

levels (Mace et al., 1999; Benfield et al., 2010; Rapoza et al., 2015; Fidell et al., 1979).

Clip sequence, or the order in which audio clips were played was an important factor in

predictive models for both acceptability and annoyance. This finding further justifies the

importance of playing a random order of varying levels of audio clips. As Pilcher et al. (2009)

suggested, the order in which audio clips are played my impact visitor response, especially if

clips are played in an ascending or descending order. These results also build upon Gibson’s

(2011) study that suggested when survey respondents are exposed to sound clips or pictures of

varying levels of impact, responses regress to the mean. Testing a wide range of sound levels that

are randomly assigned to visitors improves the validity of regression results.

For the models that predicted acceptability, and acceptability by hour and day; location or

site of the survey was an important factor. An interpretation of this finding could be that

acceptability of specific sounds change by location. For instance, propeller aircraft sounds might

95

be perceived as less acceptable while hiking when compared to hearing them outside the Muirie

Science and Learning Center. As reviewed in Zinn et al. (1998), normative beliefs related to

recreational management are influenced by situation specifics. Zinn et al.’s (1998) study found

that acceptability of mountain lion management was dependent on situational context. In this

study, the specific location of the intercept survey was important. Additionally, this finding

signifies the influence of testing visitor reaction to sounds in-situ, rather than in a laboratory

experience. Lab participants don’t have the same motivations and experiences as park visitors.

Because of this, findings from this study can be generalized to the population of visitors to

DENA.

Management implications

Results from the audio clip survey aimed to inform thresholds for aircraft noise that

management can use to better understand acceptable sounds levels for aircraft and the point at

which the number of aircraft are deemed unacceptable. Propeller aircraft sound level is predicted

to be rated as unacceptable by visitors at about 54 LAeq. These results also suggest a numerical

threshold for hearing aircraft. Hearing aircraft at three minutes per hour was slightly acceptable

for lower sound levels (<60 LAeq), and became unacceptable at higher levels (>60 LAeq).

Hearing aircraft at any sound level for 9 or more minutes per hour was rated as slightly to very

unacceptable. Hearing aircraft once per day was rated as acceptable for most sound levels, but

hearing aircraft for 10 or more times per day was rated as slightly to very unacceptable at all

sound levels. Finally, respondents were asked, after listening to the 6th sound clip, how many

overflights they could hear, as they heard in sound clip #6, before they would no longer visit the

park. Fifty-five percent of the sample indicated a specific number of flights they could hear

before they would no longer visit the park. On average this number was 45.5 flights per day.

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The next step for DENA management would be to determine if the number of flights are

currently violating thresholds. For example, how many overflights per day are heard in DENA’s

frontcountry and what are the sound levels associated with those flights. Determining a threshold

for overflights will also depend on management objectives for managing the frontcountry areas of

DENA. For example, if a management objective is to provide visitors with the ability to

experience natural quiet and sounds of nature, which is mandated by the NPS, overflight noise

might create a masking effect. Additionally, if thresholds are being violated, it is important for

management to review the amount of commercial air tours deemed acceptable, and determine the

appropriate number of take offs and landings for the airstrip located within the park. It is

important for management to monitor the sound level of takeoff and landing events that occur

within the park. It’s possible that the sound level and number of events violate thresholds and

contribute to negative soundscape experiences.

Conclusion

This study broadens the application of indicators of quality and thresholds that are used in

managing parks and protected areas. This method for informing thresholds for soundscape quality

builds on other dose response studies and is improved by the use of an extended library of

varying audio-levels. This study used general linear mixed models, as opposed to using averages,

to predict visitor response to a wide range of varying sound levels. This method proved to be

more robust and increase measurement validity. Sound level and audio clip sequence were shown

to be important variables for modeling response to sound. These findings are valuable to future

studies and signify the importance of presenting survey respondents with a random order of audio

clips.

While the results from this study are specific to frontcountry use in DENA, methods can

be adapted to other national parks. It can be applied to other parks and protected areas that are

subject to impacts from commercial aircraft tours. Moreover, the method of developing varying

97

levels of audio clips can be used for other anthropogenic soundscape indicators such as: vehicles

including personal, bus, and motorcycle, as well as voices, generators, and other aircraft types.

References

Aasvang, G. M., & Engdahl, B. (2004). Subjective responses to aircraft noise in an outdoor

recreational setting: a combined field and laboratory study. Journal of Sound and

Vibration, 276(3-5), 981-996.

Abbott, L. C., Taff, D., Newman, P., Benfield, J., & Mowen, A. (2016). The influence of natural

sounds on attention restoration. Journal of Park and Recreation Administration, 34(3), 5–

15.

Aletta, F., & Kang, J. (2015). Soundscape approach integrating noise mapping techniques: a case

study in Brighton, UK. Noise Mapping, 2(1), 1–12. https://doi.org/10.1515/noise-2015-0001

Alvarsson, J. J., Wiens, S., & Nilsson, M. E. (2010). Stress recovery during exposure to nature

sound and environmental noise. International Journal of Environmental Research and

Public Health, 7(3), 1036–1046. https://doi.org/10.3390/ijerph7031036

Anderson, G. S., Rapoza, A. S., Fleming, G. G., & Miller, N. P. (2011). Aircraft noise dose-

response relations for national parks. Noise Control Engineering Journal, 59(July), 519.

https://doi.org/10.3397/1.3622636


soundscape perception. Journal of the Acoustical Society of America, 128(5), 2836–2846.

https://doi.org/10.1121/1.3493436

Babisch, W. (2003). Stress hormones in the research on cardiovascular effects of noise. Noise &

Health, 5(18), 1–11. https://doi.org/NO_DOI

Baranzini, A., Ramirez, J., Schaerer, C., & Thalmann, P. (2008). Hedonic methods in housing

markets: Pricing environmental amenities and segregation. Hedonic Methods in Housing

98

Markets: Pricing Environmental Amenities and Segregation, (December), 1–278.

https://doi.org/10.1007/978-0-387-76815-1

Barber, J. R., Burdett, C. L., Reed, S. E., Warner, K. A., Formichella, C., Crooks, K. R., …

Fristrup, K. M. (2011). Anthropogenic noise exposure in protected natural areas: Estimating

the scale of ecological consequences. Landscape Ecology, 26(9), 1281–1295.

https://doi.org/10.1007/s10980-011-9646-7

Benfield, J. A., Nurse, G. A., Jakubowski, R., Gibson, A. W., Taff, B. D., Newman, P., & Bell, P.

A. (2014). Testing Noise in the Field: A Brief Measure of Individual Noise Sensitivity.

Environment and Behavior, 46(3), 353–372. https://doi.org/10.1177/0013916512454430

Benfield, J. A., Taff, B. D., Newman, P., & Smyth, J. (2014). Natural Sound Facilitates Mood

Recovery. Ecopsychology, 6(3), 183–188. https://doi.org/10.1089/eco.2014.0028

Bratman, G. N., Hamilton, J. P., & Daily, G. C. (2012). The impacts of nature experience on

human cognitive function and mental health. Annals of the New York Academy of Sciences,

1249(1), 118–136. https://doi.org/10.1111/j.1749-6632.2011.06400.x


experience reduces rumination and subgenual prefrontal cortex activation. Proceedings of

the National Academy of Sciences of the United States of America, 112(28), 8567–72.

https://doi.org/10.1073/pnas.1510459112

Bullock, S. D., & Lawson, S. R. (2008). Managing the “Commons” on Cadillac Mountain: A

Stated Choice Analysis of Acadia National Park Visitors’ Preferences. Leisure Sciences,

30(February 2007), 71–86. https://doi.org/10.1080/01490400701756436




Cai, M., Zou, J., Xie, J., & Ma, X. (2015). Road traffic noise mapping in Guangzhou using GIS

99

and GPS. Applied Acoustics, 87. https://doi.org/10.1016/j.apacoust.2014.06.005

Casey, J. A., Morello-Frosch, R., Mennitt, D. J., Fristrup, K., Ogburn, E. L., & James, P. (2017).

Race/ethnicity , socioeconomic status , residential segregation , and spatial variation in noise

exposure in the contiguous United States. Environmental Health Perspectives, 125(7), 1–10.

https://doi.org/10.1289/EHP898

Chemtob, C., Roitblat, H. L., Hamada, R. S., Carlson, J. G., & Twentyman, C. T. (1988). A

cognitive action theory of post-traumatic stress disorder. Journal of Anxiety Disorders, 2(3),

253–275. https://doi.org/10.1016/0887-6185(88)90006-0

Chew, Y. R., & Wu, B. S. (2016). A soundscape approach to analyze traffic noise in the city of

Taipei, Taiwan. Computers, Environment and Urban Systems, 59, 78–85.


Cohen, S., Evans, G. W., Krantz, D. S., & Stokols, D. (1980). Physiological, motivational, and

cognitive effects of aircraft noise on children: moving from the laboratory to the field. The

American Psychologist, 35(3), 231–243. https://doi.org/10.1037/0003-066X.35.3.231

Cottrell, S. P., & Meisel, C. (2003). Responsibility To Protect the Marine Environment Among

Scuba. Symposium A Quarterly Journal In Modern Foreign Literatures, 252–262.




Ferrini, S., & Scarpa, R. (2007). Designs with a priori information for nonmarket valuation with

choice experiments: A Monte Carlo study. Journal of Environmental Economics and

Management, 53(3), 342–363. https://doi.org/10.1016/J.JEEM.2006.10.007

Fidell, S., Silvati, L., Howe, R., Pearsons, K. S., Tabachnick, B., Knopf, R. C., … Buchanan, T.

(1996). Effects of aircraft overflights on wilderness recreationists. The Journal of the

Acoustical Society of America, 100(5), 2909–2918. https://doi.org/10.1121/1.417102

100

Francis, C. D., & Barber, J. R. (2013). A framework for understanding noise impacts on wildlife:

An urgent conservation priority. Frontiers in Ecology and the Environment, 11(6), 305–313.

https://doi.org/10.1890/120183

Francis, C. D., Newman, P., Taff, B. D., White, C., Monz, C. A., Levenhagen, M., … Barber, J.

R. (2017). Acoustic environments matter: Synergistic benefits to humans and ecological

communities. Journal of Environmental Management, 203, 245–254.


Freimund, W. a., Vaske, J. J., Donnelly, M. P., & Miller, T. a. (2002). Using Video Surveys to

Access Dispersed Backcountry Visitors’ Norms. Leisure Sciences, 24(3–4), 349–362.

https://doi.org/10.1080/01490400290050790

Freimund, W. A., Vaske, J. J., Donnelly, M. P., & Miller, T. A. (2002). Using video surveys to

access dispersed backcountry visitor’s norms. Leisure Sciences, 24(3–4), 349–362.

https://doi.org/10.1080/01490400290050790

Gibson, A.W. (2011) Photograph presentation order and range effects in visual based outdoor

recreation research. Colorado State University, Fort Collins, CO.

Goines, L., & Hagler, L. (2007). Noise pollution: a modern plague. Southern Medical Journal,

100(3), 287–294. https://doi.org/10.1097/SMJ.0b013e3180318be5

Haas, G. E., & Wakefield, T. J. (1998). National parks and the American public: a national public

opinion survey on the National Park System: a summary report. The Association.

Haines, M. M., Stansfeld, S. A., Job, R. S., Berglund, B., & Head, J. (2001). Chronic aircraft

noise exposure, stress responses, mental health and cognitive performance in school

children. Psychological medicine, 31(2), 265-277.

Hammer, M. S., Swinburn, T. K., & Neitzel, R. L. (2014). Environmental noise pollution in the

United States: Developing an effective public health response. Environmental Health

Perspectives, 122(2), 115–119. https://doi.org/10.1289/ehp.1307272

101

Heywood, J. L., Murdock, W. E., Heywood, J. L., & Murdock, W. E. (2002). Social Norms in

Outdoor Recreation : Searching for the Behavior-Condition Social Norms in Outdoor

Recreation : Searching for the Behavior-Condition Link, (912280237), 283–295.

https://doi.org/10.1080/01490400290050745

Hong, J. Y., & Jeon, J. Y. (2014). Soundscape mapping in urban contexts using GIS techniques.

Inter-Noise 2014, 5.

Inglis J., G., Johnson I., V., & Ponte, F. (1999). Crowding norms in marine settings: A case study

of snorkelling on the Great Barrier Reef. Environmental Management, 24(3), 369–381.

Kuss, F. R., Graefe, Alan, R., & Vaske, J. J. (1990). Visitor Impact Management: A Review of

Research.

Lee, S. W., Chang, S. Il, & Park, Y. M. (2008). Utilizing noise mapping for environmental impact

assessment in a downtown redevelopment area of Seoul, Korea. Applied Acoustics, 69(8),

704–714. https://doi.org/10.1016/j.apacoust.2007.02.009

Lex Brown, A. (2012). A review of progress in soundscapes and an approach to soundscape

planning. International Journal of Acoustics and Vibrations, 17(2), 73–81.

https://doi.org/10.20855/ijav.2012.17.2302


soundscapes in a multiple functional urban area. Landscape and Urban Planning, 115, 1–9.

https://doi.org/10.1016/j.landurbplan.2013.03.008

Mace, B. L., Bell, P. a., & Loomis, R. J. (2004). Visibility and Natural Quiet in National Parks

and Wilderness Areas: Psychological Considerations. Environment & Behavior, 36(1), 5–

31. https://doi.org/10.1177/0013916503254747

Mace, B. L., Bell, P. A., & Loomis, R. J. (1999). Aesthetic , A V ective , and Cognitive E V ects

of Noise on Natural Landscape Assessment. Society, 1920(July 1998), 225–242.

https://doi.org/10.1080/089419299279713

102

Mace, B. L., Corser, G. C., Zitting, L., & Denison, J. (2013). Effects of overflights on the national

park experience. Journal of Environmental Psychology, 35, 30–39.



Framework for Managing the Carrying Capacity of National Parks. Joumal of Park and


Manning, R. E., & Freimund, W. A. (2004). Use of visual research methods to measure standards

of quality for parks and outdoor recreation. Journal of Leisure Research, 36(4), 557–579.


Acceptability Norms of Human-Caused Sound in Muir Woods National Monument. Leisure

Sciences, 33(931379096), 147–161. https://doi.org/10.1080/01490400.2011.550224

McAlexander, T. P., Gershon, R. R. M., & Neitzel, R. L. (2015). Street-level noise in an urban

setting: Assessment and contribution to personal exposure. Environmental Health: A Global

Access Science Source, 14(1), 1–10. https://doi.org/10.1186/s12940-015-0006-y

Mennitt, D., Fristrup, K., Sherrill, K., & Nelson, L. (2013). Mapping sound pressure levels on

continental scales using a geospatial sound model. Internoise, (January), 1–11.

https://doi.org/10.1371/journal.pone.0004065

Mennitt, D. J., & Fristrup, K. M. (2016). In fl uential factors and spatiotemporal patterns of

environmental sound levels in the contiguous United States, (May).

Mennitt, D., Sherrill, K., & Fristrup, K. (2014). A geospatial model of ambient sound pressure

levels in the contiguous United States. The Journal of the Acoustical Society of America,

135(5), 2746–64. https://doi.org/10.1121/1.4870481

Merchant, N. D., Fristrup, K. M., Johnson, M. P., Tyack, P. L., Witt, M. J., Blondel, P., & Parks,

S. E. (2015). Measuring acoustic habitats. Methods in Ecology and Evolution, 6(3), 257–

265. https://doi.org/10.1111/2041-210X.12330

103

Miller, N. (2003). Transportation noise and recreational lands. Noise/News International, 9–21.

Retrieved from http://www.hmmh.com/cmsdocuments/N011.pdf

Miller, N. P. (1999). The effects of aircraft overflights on visitors to US National Parks. Noise

Control Engineering Journal, 47(3), 112–117. https://doi.org/10.3397/1.599294

Miller, N. P. (2008). US National Parks and management of park soundscapes: A review. Applied

Acoustics, 69(2), 77–92. https://doi.org/10.1016/j.apacoust.2007.04.008



https://doi.org/10.1007/s13398-014-0173-7.2

Newman, P., Manning, R., Donald, D., & Mckonly, W. (2005). Decision Making in Yosemite

National Park , USA Using Stated Choice Modeling. Journal of Park and Recreation


Park, L., Lawson, S., Kaliski, K., Newman, P., & Gibson, A. (2010). Modeling and mapping

hikers ’ exposure to transportation noise in Rocky Mountain National Park. Park Science,

26(3), 1–11. Retrieved from http://nova.wh.whoi.edu/palit/Park et al_2010_Park

Science_Modeling and mapping hikers ? exposure to transportation noise in Rocky

Mountain National Park.pdf

Park, L. O., Manning, R. E., Marion, J. L., Lawson, S. R., & Jacobi, C. (2008). Managing Visitor

Impacts in Parks : A Multi-Method Study of the Effectiveness of Alternative Management

Practices. Journal of Park and Recreation Administration, 26(1), 97–121.

Pedersen, E., & Persson Waye, K. (2004). Perception and annoyance due to wind turbine noise—

a dose–response relationship. The Journal of the Acoustical Society of America, 116(6),

3460-3470.

Pepper, C. B., Nascarella, M. A., & Kendall, R. J. (2003). A review of the effects of aircraft noise

on wildlife and humans, current control mechanisms, and the need for further

104

study. Environmental Management, 32(4), 418-432.

Pettebone, D., Newman, P., Lawson, S. R., Hunt, L., Monz, C., & Zwiefka, J. (2011). Estimating

visitors’ travel mode choices along the Bear Lake Road in Rocky Mountain National Park.

Journal of Transport Geography, 19(6), 1210–1221.


Pijanowski, L., Villanueva-rivera, B. C., Dumyahn, S. L., Farina, A., Krause, B. L., Napoletano,

B. M., … Pieretti, N. (2011). SoundScape Ecology : The Science of Sound in tiie

Landscape, 61(3), 203–216.

Pilcher, E. (2006). Visitor Experience and Soundscapes : Annotated Bibliography. Noise Control

Engineering.

Pilcher, E. J., Newman, P., & Manning, R. E. (2009). Understanding and managing experiential

aspects of soundscapes at muir woods national monument. Environmental Management,

43(3), 425–435. https://doi.org/10.1007/s00267-008-9224-1

Plotkin, K. J. (2001). The Role of Aircraft Noise Simulation Models. The 2001 International

Congress and Exhibition on Noise Control Engineering, 10(1).

Rapoza, A., Sudderth, E., & Lewis, K. (2015). The relationship between aircraft noise exposure

and day-use visitor survey responses in backcountry areas of national parks. Journal of the

Acoustical Society of America, 138(4). https://doi.org/10.1121/1.4929934

Schomer, P., Mestre, V., Schulte-Fortkamp, B., & Boyle, J. (2013). Respondents’ answers to

community attitudinal surveys represent impressions of soundscapes and not merely

reactions to the physical noise. The Journal of the Acoustical Society of America, 134(1),

767–772. https://doi.org/10.1121/1.4808075

Shannon, G., Crooks, K. R., Wittemyer, G., Fristrup, K. M., & Angeloni, L. M. (2016). Road

noise causes earlier predator detection and flight response in a free-ranging mammal.

Behavioral Ecology, 27(5), 1370–1375. https://doi.org/10.1093/beheco/arw058

105


Coefficient Alpha and Successor Procedures”Lee J. Cronbach 1916-2001. Educational and

Psychological Measurement, 64(3), 389–390. https://doi.org/10.1177/0013164404264117

Shelby, B., Vaske, J. J., & Donnelly, M. P. (1996). Shelby et al (1996) - Norms, standards _

natural resources.pdf.

Stack, D. W., Peter, N., Manning, R. E., & Fristrup, K. M. (2011). Reducing visitor noise levels

at Muir Woods National Monument using experimental management. The Journal of the

Acoustical Society of America, 129(3), 1375–1380. https://doi.org/10.1121/1.3531803

Stankey, G. H., Cole, D. N., Lucas, R. C., Petersen, M. E., & Frissell, S. S. (1984). The limits of

acceptable change (LAC) system for wilderness planning: Volume 176 of General technical

report INT. General Technical, 176, 37.

Taff, D., Newman, P., Lawson, S. R., Bright, A., Marin, L., Gibson, A., & Archie, T. (2014). The

role of messaging on acceptability of military aircraft sounds in Sequoia National Park.

Applied Acoustics, 84, 122–128. https://doi.org/10.1016/j.apacoust.2013.09.012

Tarrant, M. A., Haas, G. E., & Manfredo, M. J. (1995). Factors Affecting Visitor Evaluations of

Aircraft Overflights of Wilderness Areas. Society & Natural Resources, 8(4), 351–30.

Theebe, M. A. J. (2004). Planes, Trains, and Automobiles: The Impact of Traffic Noise on House

Prices. The Journal of Real Estate Finance and Economics, 28(2/3), 209–234.

https://doi.org/10.1023/B:REAL.0000011154.92682.4b

Trojanek, R., Tanas, J., Raslanas, S., & Banaitis, A. (2017). The Impact of Aircraft Noise on

Housing Prices in Poznan. Sustainability, 9(11), 2088. https://doi.org/10.3390/su9112088

Vaske, J. J., & Donnelly, M. P. (2002). Visitor Crowding and Normative Tolerances at Congested

Areas of Rocky Mountain National Park Xinran Lehto Assistant Professor Department of

Natural Resource Recreation and Tourism Human Dimensions in Natural Resources Unit

Colorado State University, (May).

106

Weinzimmer, D., Newman, P., Taff, D., Benfield, J., Lynch, E., & Bell, P. (2014). Human

Responses to Simulated Motorized Noise in National Parks. Leisure Sciences, 36(3), 251–

267. https://doi.org/10.1080/01490400.2014.888022

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Chapter 4 Visitor Preferences for Soundscape Management in Muir Woods National

Monument



RQ1: What tradeoffs are visitors willing to make in order to hear natural sounds

in Muir Woods National Monument?

RQ2: Are the trade-offs made by visitors different in the treatment group (signs

present asking visitors to maintain quiet) vs. the control group (all signs are

covered)?

Abstract: National Park managers are mandated to protect natural sounds for both

wildlife and visitor experience. Enjoying natural quiet and sounds of nature is an

important motivation for visitors to National Parks. Researchers have used both policy

and studies of visitor motivations to justify the significance of protecting natural sounds.

The purpose of this study was to explore the tradeoffs visitors make in order to achieve a

more natural soundscape. Do visitors support more intensive interventions from

management in order to hear more natural sounds? This study also tested the differences

in preferences between respondents who were exposed to educational signs that asked

visitors to be quiet and respondents who didn’t view any signs. Results indicated that

respondents preferred indirect forms of management, such as educational signs and

rangers asking visitors to maintain quiet in the park. Additionally, respondents who were

exposed to signs, had a significantly higher preference for indirect management

interference than the control group who was not exposed to signs.

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Introduction

In 2016 the National Park Service (NPS) celebrated their 100th anniversary. The

celebration and extra promotion of National Parks led to a record breaking year with over

330 million recreation visits (NPS, 2018). In general, visitation to National Parks has

been increasing (Warnick, et al. 2012) and thus making the NPS mission difficult to

achieve. Park managers are tasked with ensuring the balance of protecting natural and

cultural resources, while providing positive experiences for park visitors. Soundscapes,

defined as the acoustic environment (Newman, Manning, & Trevino, 2009, p. 2), are

included in the list of resources managers are tasked with preserving for the enjoyment of

future generations. With record numbers of visitors traveling to national parks, natural

soundscapes are masked by transportation and other noise caused by visitors. In fact,

elevated levels of noise have been estimated to impact a large portion of protected area

units (Buxton et al., 2017).

Visitors choose to recreate in National Parks for a number of different reasons,

but the motivation to enjoy quiet and natural sounds is common among visitors (Haas &

Wakefield, 1998; Marin et al., 2011). Natural soundscapes have also been shown to

provide humans with benefits. For example, natural sounds such a birdsong, have been

found to improve mood (Benfield, Taff, et al., 2014), cognitive restoration (Abbott et al.,

2015), and landscape assessment (Weinzimmer et al., 2014). Conversely, anthropogenic

or man-made sounds can negatively impact physiological measures, such as stress and

heart rate (Hammer et al., 2014). Sounds from sources such as aircraft and transportation

have been found to impede on positive park experiences (Mace et al., 2013; Tarrant,

Haas, & Manfredo, 1995). Sounds from visitors talking have also been identified as a

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factor that impacts the natural soundscape and positive experiences (E. J. Pilcher et al.,

2009).

Motivations have been used as a powerful tool in understanding the important

reasons visitors travel to national parks, which includes the opportunity to hear natural

sounds. However, these data tell us little about the value park visitors place on

soundscapes and protecting them. Past research has shown that park visitors are willing to

make tradeoffs in order to achieve desired experiences (Bullock & Lawson, 2008;

Newman, Manning, Dennis, & Mckonly, 2005; Newton et al., In press; Pettebone et al.,

2011). Stated choice modeling has been used to measure visitors’ preferences and

tradeoffs for social, natural, and managerial experiences in parks.

Park managers use multiple strategies to improve the quality of park resources,

this includes different levels of management interference. Management strategies can be

more “heavy handed” and infringe on visitor freedoms. While other strategies are

considered “light handed”, where education can be used to achieve management

objectives. The purpose of this paper is to explore the tradeoffs visitors make to achieve a

high-quality soundscape experience and the levels of management that are most

preferred.

Literature

Soundscape Management

Similar to other natural resources like wildlife and water, NPS managers aim to

protect natural sounds. The NPS Soundscape Management Policy 4.9 requires National

Park units to measure acceptable sound levels and mitigate noise (NPS, 2006).

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Soundscape management is important for maintaining both wildlife habitat (Francis &

Barber, 2013) and quality visitor experiences. Visitor Experience and Resource

Protection (VERP) is the specific framework used by the NPS for managing carrying

capacity and other issues related to increased visitor use (Manning, 2001). This

framework has been used to measure and mitigate anthropogenic sounds that threaten the

sustainability of quality park experiences.

Pilcher, Newman, & Manning (2009), used the VERP framework to identify

indicators and thresholds for soundscape quality in Muir Woods National Monument.

Noise from other visitors (talking, screaming, etc.) was identified as a potential indicator

of quality. This study also determined a threshold for soundscape quality based on sound

levels produced by visitors in the park. Ultimately, these thresholds were being violated

by increased sound levels caused by visitors. A follow up study aimed to reduce noise

caused by visitors through testing the efficiency and acceptability of signs that asked

visitors to be quiet (Stack et al., 2011). This study used an experimental design to test

differences in park sound levels and visitor response to the signs. The educational signs

were found to be effective in lowering sound levels in the park. Visitor noise decreased

by 3 dB(A), which then doubled the opportunity for visitors to hear natural sounds.

Additionally, visitors were highly supportive of the signs as a management practice.

Management Strategies

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In order to achieve the balance of resource protection and quality visitor experience,

researchers and managers have been tasked with understanding the effectiveness of

different strategies for managing human behavior (Bullock & Lawson, 2008; Park,

Manning, Marion, Lawson, & Jacobi, 2008) . This topic is reviewed in Manning (2011),

essentially there is a spectrum of strategies that span between “heavy handed” or direct

approaches and “light handed” or indirect approaches. Direct management strategies

apply regulatory measures to change visitor behavior, while indirect strategies aim to

impact visitors’ decision-making process to influence behavior (Manning, 2011). An

example of a direct management strategy would be closing a specific trail to reduce

crowding or restore a trail from human impact (Hockett, Marion, & Leung, 2017).

Informational or educational signs are a form of indirect management that can alter

visitor attitudes or perceptions (Manning, 2003).

In some cases, an experimentally designed study is used to test the effectiveness of

different direct and indirect management treatments. Park et al. (2008) tested visitor

behavior outcomes related to either direct (closed trails) or indirect (educational)

treatments to keep visitors from hiking off trail. Within the context of soundscape

management, Stack et al. (2011) also used an experimental design to test the

effectiveness of educational signs in MUWO that denoted either a “quiet zone” or a

“quiet day”. Results demonstrated that indirect management in the form of educational

signs to be effective in lowering park sound levels. Additionally, visitors found the signs

to be an acceptable management intervention. In another study, Taff et al., (2014), used

educational messaging in Sequoia National Park to improve visitors’ acceptability of

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military aircraft noise. The results of these studies suggest that indirect management is

useful for shifting visitor behavior and perceptions of park soundscapes.

Stated Choice Modeling.

Stated choice modeling was initially used in market research to understand

preferences in product design (Louviere, Hensher, & Swait, 2000). This method is used

to help researchers understand how people evaluate choices and the tradeoffs they make

in order to obtain the best possible condition. Respondents of stated choice surveys are

asked to make a series of distinct choices between two or more scenarios that have

multiple levels of attributes. For example, when buying a new car, one has the option of

choosing from an overwhelming number of accessories (i.e. leather interior, power

windows, satellite radio, etc.). The method of stated choice modeling can tell us about the

types of choices and “trade-offs” a sample of consumers might make. These results aid in

more precise product development and manufacturing.

This method has also been applied to park and recreation management (Bullock &

Lawson, 2008; Newman, Manning, Dennis, & Mckonly, 2005; Newton et al., In press);

Pettebone et al., 2011). Rather than measuring preferences for products, stated choice has

been used to measure visitors’ preferences and tradeoffs for social, natural, and

managerial experiences in parks. Newman et al. (2005) studied the tradeoffs of

backcountry users in Yosemite National Park’s wilderness areas. This study used a

survey with paired comparisons to determine respondents rated signs of human use at

backcountry campsites to be an important indicator of quality. Moreover, this method

allowed for researchers to provide Yosemite National Park management with the results

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of the model, which indicated that respondents were willing to deal with more stringent

management in order to gain quality in the appearance of campsites.

In another study, Bullock and Lawson (2008), used stated choice to understand

visitor preferences for management at Cadillac Mountain, in Acadia National Park.

Attributes for management conditions included varying levels of management

interference, ranging from freedom and open access to turning many visitors away from

visiting the summit during busy times. The study also included attributes for social

conditions (the number of people on the trail) and resource conditions that reflected

varying levels of visitor caused environmental damage. During data collection,

respondents were presented scenarios that described a narrative of varying attributes, as

well as, a photo that portrays the attribute narrative. Results from this study identified

visitors’ preference towards protecting the environmental resources on the summit.

Additionally, they are in favor of rigorous management implications, but prefer the

summit to be open access. These findings allow for management to understand the

specific preferences of victors to this iconic park summit.

Researchers have also used stated choice modeling to understand park visitor

preferences off the trail. Pettebone et al. (2011) used this method to investigate visitors’

preference for traveling within the Bear Lake Road area of Rocky Mountain National

Park. Due to increased use, the NPS is using alternative transportation, like bus systems,

to move visitors through parks. This study analyzed varying attributes related to

destination convenience, traffic and visitor volume, and number of hikers on a trail.

Photos were also utilized to depict different scenarios. Results from this study found that

visitors prefer to use their personal vehicles in the park. They were willing to tradeoff

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using their personal vehicle and use the bus transportation to avoid congestion on the

roads and trails. These data were useful to managers who can then use this information to

design a transportation system and encourage visitors to use the bus rather than deal with

vehicle traffic.

Study Justification

Golden Gate National Recreation Area, located north of San Francisco, held first

place for recreation visits in 2016 with over 15 million visits (NPS, 2017). Visitation at

nearby Muir Woods National Monument (MUWO) has also been steadily increasing and

exceeds one million visits per year (NPS, 2017). Due to increased visitation to this

relatively small park, reservations are now required for all personal vehicles and shuttle

riders visiting MUWO. MUWO management values the protection of natural sounds and

has made a concerted effort to improve the natural soundscape using empirical evidence.

The Cathedral Grove section of the park is a designated “quiet zone”. This was a result of

Stack et al.’s (2011) study that informed the success of using educational signage to quiet

visitors.

To date no study has used stated choice modeling to understand if visitors are willing

to make tradeoffs in order to experience a more natural soundscape. The purpose of the

study was to explore tradeoffs at MUWO, a park with growing visitation and potentially

increased noise levels. Similar to Stack et al., (2011), an experimental design was used to

test differences in tradeoffs on days when educational signs were present (treatment) and

days when signs were covered (control). The study answers two questions:

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Research Questions

RQ1: What tradeoffs are visitors willing to make in order to hear natural sounds in


RQ2: Are the trade-offs made by visitors different in the treatment group (signs

present asking visitors to maintain quiet) vs. the control group (all signs are covered)?

Methods

Study Site

Visitor intercept surveys were collected in the summer of 2016 at Muir Woods

National Monument (MUWO), which is located north of San Francisco, California (See

Figure 4-1). MUWO is a popular destination for tourists and includes 500 acres of

redwood trees, with hiking trails throughout. People are drawn to this park to experience

the towering and awe inspiring old growth coastal redwood forest. MUWO is also a park

that is keen on protecting its natural sounds. Since 2005, the park has supported a number

of different soundscape related studies (Marin et al., 2011; E. Pilcher, 2006; Stack, Peter,

Manning, & Fristrup, 2011). For example, a study conducted by Stack et al. (2011), used

signs asking visitors to keep quiet to test whether or not they were effective and quieting

visitor noise and improving visitors’ experiences. They found a significant decrease in

sound level with the presence of this signage. Results from this research led to the park’s

use of permanent signs that name the cathedral grove area of the park a “quiet zone”.

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Figure 4-1. Map of San Francisco Area

Experimental Design

Similar to methods used by Stack et al. (2011), educational treatments were used

to designate “quiet days” (treatment) and “control days” during the study period.

Treatment and control mitigations were used in week long blocks. During the treatment

or “quiet” days, educational A-frame signs (e.g., ‘Enter Quietly’, ‘Maintain Natural

Quiet’, ‘What you can do to help natural soundscapes’) along a ~0.6 km segment of the

main trail system (See Figure 4-2). During control days, all educational signs related to

maintaining quiet were removed or covered.

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Figure 4-2. Educational Signs (used in treatment weeks)

Survey Administration

Visitors were intercepted and asked to participate in the survey as they were

exiting the trail corridor. Sampling days were stratified by weekend and weekday, control

and treatment, and time of day. Survey participants were given a laminated copy of the

survey questionnaire. The research assistants read the instructions and used tablet

computers to input the responses. Tablets are used to facilitate skip patterns and minimize

data entry errors.

The survey included measures of visitor motivations, interpretation of the park

soundscape, noise sensitivity and questions to determine tradeoffs for preferred

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experiences. Tradeoff modeling attributes were chosen for this study based on realistic

management scenarios and varying ranges of acoustical environments (See Figure 4-3).

These attributes included 1) percent time hearing natural sounds, 2) varying degrees of

management actions, and 3) temporal trail closures.

Choice Experiment Design

The experimental design for choice models is an important step in the survey

planning phase. Essentially, it is unreasonable to ask survey respondents to respond to all

possible variations of the choice attributes that are presented in Figure 4-3. Moreover, the

design of choice sets should aim to reduce the amount of mental effort needed to respond,

so as to not impair respondents’ cognitive ability (Ferrini & Scarpa, 2007). The goal of

model design is to develop a condensed collection of discrete choice scenarios that are

manageable for an intercept survey and will best measure respondents’ tradeoffs. An

efficient design was used to determine which attribute combinations will most effectively

measure the sample populations’ tradeoffs among attributes.

We used an efficient design to create choice scenarios that would best measure

visitor preferences. Efficient designs “maximize the information from each choice

situation” and are tested for their level of efficiency using the D-statistic (Rose &

Bliemer, 2009, p.590). This method accounts for random parameters, as well as,

estimated sample size to develop blocks of multiple-choice scenarios. The design was

generated using Ngene (D-error = 0.7836). Initially, 18 choice sets were developed and

then blocked into two survey versions. Each respondent reviewed nine paired

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comparisons and were asked to choose which scenario they most preferred (See Figure 4-

4). Moreover, respondents did not have the option to choose neither scenario if both were

not preferred.

Variable Levels

Per

cent

Tim

e

hea

ring N

atu

ral

Sounds

1 You can hear natural sounds (e.g. birdsong, small mammals) most of the time

(about 75% of the time)

2 You can hear natural sounds (e.g. birdsong, small mammals) about half of the

time (about 50% of the time)

3 You can hear natural sounds (e.g. birdsong, small mammals) some of the time

(about 25% of the time)

4 You can rarely hear natural sounds (e.g. birdsong, small mammals) (about 5%

of the time)

Man

agem

ent

Act

ions

1 No signs are posted along the trail about natural quiet

2 Signs are posted along the trail educating visitors about natural quiet

3 Signs are posted along the trail educating visitors about natural quiet & asking

visitors to limit noise


visitors to limit noise, and rangers are stationed along the trail to limit visitor

caused noise


visitors to limit noise, and rangers are enforcing visitors to limit their noise

along the trail

Tem

pora

l

Clo

sure

s 1 Trails are open during operating hours

2 Trails are closed for one hour after dawn for the morning breeding bird chorus

3 Trails are closed for one hour after dawn & one hour before evening for the

breeding bird chorus

Figure 4-3. MUWO Stated Choice Attributes

120

Figure 4-4. Example of choice scenario

Model Analysis

The results of respondents’ scenario choices were analyzed using a random

parameter logit model. This model type assumes the marginal utility of each of the

attributes to have normal distribution and unobserved variability among survey

respondents (Reviewed in Shr and Read, 2016). Marginal utility scores represent the level

of importance respondents place on each attribute. In preparation for model analysis, data

from the preferred management scenarios were dummy coded (Louviere et al., 2001).

Essentially, the scenario chosen by each respondent was treated as the dependent variable

and coded as either “1” or “0”. The independent variables represented the varying levels

of acoustic and management indicators. These were also labeled with effect codes so that

the base or reference level of each indicator is omitted in the estimation, while the

coefficients of the base level are calculated by the negative sum of all other coefficients

of other levels.

121

In this study, the first level was used as the reference (e.g. “No signs are posted

along the trail about natural sound” and “Trails are open during operating hours”). That is

to say, base attributes were treated as the “cost” for achieving other attributes. For

example, respondents might prefer to see signs along the trail and ranger enforcement of

quiet to avoid trail closures at dawn and dusk. Utility scores were generated by regressing

the effect coded variables.

One of the main goals of this stated choice analysis was to measure the

differences between the treatment and control group. This was achieved by fixing the

parameters for natural sound. It was assumed that results from the natural sound attribute

would be non-random. In other words, we speculated that respondents in either group

would have the same preference for sound. This strategy allowed for a comparison

between utility scores for the treatment and control groups.

Results

Sample Profile

Visitor-intercept surveys in MUWO were collected between May 9th and May

21th, 2016. A total of 537 (n=537) surveys were collected with a 55% response rate. This

response rate is low for intercept surveys in National Parks, but it is similar to other

studies that have been conducted in Muir Woods (Marin et al., 2011; Stack et al., 2011).

Of the respondents who answered demographic questions, 84% reported living in the

United States and 16% lived outside of the United States. Forty six percent of the sample

reported their gender as male and 54% reported gender as female. The mean age was 45

122

years old, and ranged between 18 and 92 years of age. Sixty four percent of respondents

were first time visitors to MUWO. On average, visitors spent 2.18 hours in the park, and

ranged between 1 and 6 hours. We also asked visitors “How would you describe your

group?” Sixty-five percent of respondents described their group as family. Eighteen

percent reported being with friends, 6.6% were alone, and 7% were with family and

friends. Less than one percent reported their group as a commercial tour group.

Stated Choice Model

In Table 4-1, results of the random parameter logit model are presented. The

mean coefficient associated with each attribute indicates relative importance or the

“marginal utility score” of the attribute. The further the coefficient is from zero, the

higher the relative importance. The direction of the mean coefficient relates to either a

positive or negative preference. Additionally, in this model, the attributes for natural

sound were condensed and treated as a continuous variable because the attribute levels

are considered linear (e.g. “You can hear natural sounds 75% of the time”).

Results from Table 4-1 depicts the model results for both the treatment and

control group. The fixed mean score for the natural sound attribute was positive. Based

on previous literature this finding is intuitive, in that visitors would have a higher

preference for hearing natural sounds a larger percent of the time. Results related to each

group of attributes are discussed in the following sections.

123

Table 4-1. Parameter Estimates for the Latent Class Model

Treatment (Signs Displayed) Control (No Signage)

Choice Attributes Mean

(Std. Err.)

Std. Dev.

(Std. Err.)

Mean

(Std. Err.)

Std. Dev.

(Std. Err.)

Natural Sounds

You can hear natural sounds (e.g.

birdsong, small mammals) X% of the

time (Condensed)

0.176***

(0.02)

0.106***

(0.018)

Fixed across groups

Management strategies

1.No signs are posted along the trail

about natural quiet

-- -- -- --

2. Signs are posted along the trail

educating visitors about natural quiet

1.692***

(0.258)

1.373***

(0.371)

1.257***

(0.278)

1.535***

(0.392)


educating visitors about natural quiet and

asking visitors to limit noise.

2.606***

(0.230)

0.670*

(0.375)

1.953***

(0.220)

0.691**

(0.341)



asking visitors to limit noise, and rangers

are stationed along the trail to limit visitor

caused noise.

2.015***

(0.269)

1.966***

(0.300)

1.723***

(0.294)

2.230***

(0.524)



asking visitors to limit noise, and rangers

are enforcing visitors to limit their noise

along the trail.

1.143***

(0.288)

2.163***

(0.341)

0.487

(0.329)

2.618***

(0.455)

Closures

1. Trails are open during operating hours -- -- -- --

2. Trails are closed for one hour after

dawn for the morning breeding bird

chorus

0.163

(0.215)

1.151***

(0.283)

0.115

(0.231)

1.418***

(0.280)

3. Trails are closed for one hour after

dawn & one hour before evening for the

breeding bird chorus

0.092

(0.237)

1.281***

(0.301)

0.303

(0.259)

1.765***

(0.265)

Number of choice questions 4296

Number of parameters 43

Log-likelihood ratio -2113.28

Pseudo R2 0.2873

Note: ***, **, * significant at 1%, 5%, and 10%, respectively; all parameters are assumed to be normally

distributed, while correlations are allows only within the levels of each attribute.

124

Table 4-2. Differences in marginal utility scores between the treatment and control groups

Choice Attributes Difference Asymptotic t-

ratioᵃ

p-value

Management strategies

1.No signs are posted along the trail about natural

quiet

-- -- --

2. Signs are posted along the trail educating visitors

about natural quiet

0.435 3.233 0.001


about natural quiet and asking visitors to limit

noise.

0.653 10.388 0.000



noise, and rangers are stationed along the trail to

limit visitor caused noise.

0.292 1.504 0.133



noise, and rangers are enforcing visitors to limit

their noise along the trail.

0.656 2.956 0.003

Closures

1. Trails are open during operating hours -- -- --

2. Trails are closed for one hour after dawn for the

morning breeding bird chorus

0.048 0.402 0.688

3. Trails are closed for one hour after dawn & one

hour before evening for the breeding bird chorus

-0.211 -1.480 0.140

ᵃ The sample sizes used to calculate the t-ratios are the number of the respondents for each of the group

Preferences for management

Results from Table 1 show that respondents in both the treatment and control

groups most preferred Management Strategy 3, signs posted along the trail educating

visitors about quiet and asking visitors to limit noise. The mean estimate is positive and

well above zero, indicating a strong preference (Mean=2.606 for treatment group and

1.973 for the control). The standard deviations for both of these mean scores are

significant and smaller than the mean. This indicates that a large portion of the

125

respondents indicated a strong, positive preference for this attribute. Large standard

deviation scores in Table 4-1 suggest variability in responses to specific attributes. For

example, in Management Strategy 5, the mean coefficient for the control group is 0.487

and the standard deviation is 2.618. This suggests heterogeneity in preferences across

respondents. A large proportion of the control group either had high or low utility for this

attribute.

The treatment group also showed a high preference for Management Strategy 4,

which is similar to Strategy 3, but rangers are stationed along the trail asking visitors to

be quiet. This means that visitors preferred forms of indirect management through

educational signs and ranger presence. Additionally, both groups had low utility scores

for option 5, signs are posted along the trail educating visitors about natural quiet &

asking visitors to limit noise, and rangers are enforcing visitors to limit their noise.

Option 5 is a more extreme form of direct management. In other words, if rangers were

enforcing visitors to limit noise, they would no longer have a choice for how they chose

to behave in the park. Direct management is considered a more “heavy” handed approach

to visitor use issues (Manning, 2011). The standard deviations for both groups were also

large and significant, indicating variability across respondents. Finally, none of the utility

scores for management attributes were negative. It is difficult to determine a logical

tradeoff because none of the attributes are attributed to a strong, negative utility.

Table 4-2 shows the comparison between preferences for choice attributes in the

treatment and control groups. There were significant differences between groups for

Management Scenarios 2, 3, and 5. Generally, respondents in the treatment group had a

higher preference for direct (signs are posted along the trail educating visitors about

126

natural quiet & asking visitors to limit noise, and rangers are enforcing visitors to limit

their noise ) and indirect management scenarios (signs posted along the trail educating

visitors about quiet and asking visitors to limit noise. ) than the control group. However,

there was not a significant difference between groups for Management Strategy 4, signs

are posted along the trail educating visitors about natural quiet and asking visitors to

limit noise, and rangers are stationed along the trail to limit visitor caused noise.

Preferences for Park Closure

Results from choice attributes related to park closure show relatively weak

marginal utility scores (Table 1). For both the treatment and control group, mean

coefficients were positive, but not significant, meaning they were not much different

from 0, indicating low utility. These results were not expected. Previous research

suggests that direct management strategies, such as park closures, would be very much

unwanted by respondents. As to say, respondents would not be supportive of park closure

in order to hear more natural sound or vice versa. Low mean coefficients and relatively

large, significant standard deviations suggest heterogeneity across respondents. In other

words, a large portion of respondents have either a more positive or more negative utility

for the closure attributes.

Moreover, there were no significant differences between treatment and control

groups in their preferences for closure attributes (Table 4-2). This indicates that the

closure attributes were inadequate indicators of choice preference. The closure attributes

yielded no sensible tradeoffs. This may be due to poor design or measurement errors.

127

Discussion

The purpose of this study was twofold, to understand tradeoffs visitors are willing

to make in order to hear natural sound and the differences in visitor preferences between

the treatment group (signs present asking visitors to maintain quiet) and the control group

(all signs are covered). The following section discusses study results, management

implications, and a direction for future research.

RQ1: What tradeoffs are visitors willing to make in order to hear natural sounds in Muir

Woods National Monument?

Based on results from these data, visitors who experienced both treatment and

control scenarios in the park preferred indirect forms of management. From these

findings we can predict that visitors will most likely prefer to see educational signs and

rangers that ask people to be quiet in order to hear a higher percent of natural sound.

Results from the random parameter logit model did not yield any clear tradeoffs. All

marginal utility scores were positive, suggesting respondents did not strongly dislike or

disapprove of any of the proposed management attributes. However, we are able to

interpret preferences and there was a clear strong, positive preference for educational

signage. Stack et al.’s (2011) study had similar findings related to educational signs. On

both treatment and control days, respondents rated the signs as highly acceptable.

Generally, park visitors find indirect forms of management to be desirable if they are

believed to be effective (Reviewed in Manning, 2011). Other studies have found that

visitors have a higher preference for indirect over direct management strategies (Lucas,

1983).

128

Most studies related to visitor attitudes towards management focus on the

backcountry setting. The current study, conducted at MUWO, is a frontcountry park. In

other words, MUWO is considered part of a more developed area and hiking trails are

relatively short. However, some studies have addressed visitors’ preferences in the

frontcountry. For example, Bullock & Lawson (2008), found that visitors to a popular

peak in Acadia National Park preferred direct forms of management for mitigating hiking

trail impacts. Riper, Manning, Monz, & Goonan (2011), had similar findings; park

visitors preferred direct forms of management. This is different from our results that

show visitors have less preference for rangers that enforce quiet, which is a form of direct

management. It’s possible that visitors generally have different attitudes towards

soundscape management when compared to managing trail impacts or crowding.

Attributes related to park closure were relatively weak and provided little

information related to visitor tradeoffs. This is likely linked to two existing conditions.

First, currently the park’s operating hours are from 8:00AM to 5:00PM. Essentially, this

management action already exists. Second, the majority of visitors were traveling from

San Francisco or other nearby areas and would

RQ2: Are preferences different for visitors in the treatment group (signs present asking

visitors to maintain quiet) vs. the control group (all signs are covered)?

Results from the comparison of preferences in management choice attributes

between the treatment and control groups were significant for 3 of the 5 scenarios. The

treatment group had significantly stronger marginal utility scores for these attributes. In

other words, the respondents who were exposed to “quiet” signs were more supportive of

129

management interventions than the group who was not exposed to signs. Another way of

interpreting these results is by understanding the environmental changes that were a result

of the two management strategies. In Stack et al.’s (2011) study, educational signs were

shown to lower the overall sound level of the park by 3 dB(A). Three doesn’t sound like a

significant change, however, if noise is lowered by 3 dB(A), the listening area for

humans is doubled. We can assume that the signs used in our study had a similar effect

and during treatment days, visitors’ opportunity to hear natural sounds were doubled

when compared to control days. It’s possible that preference for signs were higher

because visitors were experiencing a quieter, more enjoyable soundscape. They were also

able to experience the effectiveness of the signs.

Reducing visitor noise is perceived as an issue that visitors can immediately

address through their own control. Moreover, the feedback is instant. If you quiet

yourself and your party, you can instantly hear more natural sounds. Support for

soundscape management in the forms of signs could have been a preferred option for the

treatment group because they were experiencing the outcomes of a quieted acoustic

environment.

Management Implications

This study built on methods used by Stack et al. (2011), to test visitors’ response

to educational signage. Rather than testing visitors’ acceptability of signs as a form of

indirect management, our study used stated choice modeling to understand visitor

preferences and tradeoffs related to achieving a more natural soundscape. Respondents

130

who viewed signs and were potentially exposed to a quieter soundscape had a higher

preference for viewing educational signs than the control group. These findings suggest

visitors prefer educational signs asking other visitors to be quiet because they view them

as effective and the positive feedback is immediate. Managers as MUWO already use

signs in the Cathedral Grove section of the park. This area is a designated “quiet zone”.

Our results show a higher preference for educational signs, therefore managers should

consider using educational signs throughout the park. Other National Park units and

protected areas that are similar in size to MUWO and provide a frontcountry experience

should consider using educational signs to mitigate noise created by visitors.

Ultimately, respondents had positive preferences for both direct management

practices, such as ranger presence and enforcement, as well as, indirect (educational

signs). Moreover, there were no significant, negative preferences towards park closures.

Respondents’ support for natural sound management strategies suggest the overall value

visitors are placing on protecting natural sound conditions. Park managers can determine

which management approach is deemed acceptable by visitors or is the most effective in

quieting the soundscape. Similar to Park et al. (2008), different management techniques

can be tested using an experimental design.

Limitations and future research

While this study was useful for informing preferences related to soundscapes, it

does have some limitations that merit discussion. The results suggest that the stated

choice attributes related to closure were perhaps too similar to existing management

131

conditions. As mentioned earlier, the park’s hours are 8:00am to 5:00pm which are

similar to the closing times outlined in our attributes. This is perhaps why these attributes

did not yield any significant results. This study could have benefitted from investing

other management attributes that would alter the park soundscape. One attribute could

have been related to limiting the number of visitors allowed on the trail corridor at one

time. This would have been an example of a direct management strategy that would limit

noise, but also extremely limit visitor freedom.

The model used to analyze the stated choice data did not provide any clearly

interpreted tradeoffs. Future research should use an alternative approach to analyzing the

data in order to tease out any possible tradeoffs. A latent class logit model or additional

modeling strategy that accounts for differences among respondent demographics will be

tested.

Conclusion

This study is the first of its kind to investigate visitor preferences related to

soundscapes. Our results show that visitors prefer educational signs and interference from

management to experience a quieter soundscape. Additionally, the experimental design of

the study determined that the presence of educational sings had a significant influence on

choice preferences related to soundscape management. The benefits of experiencing

natural sounds are vast. Management implications from this study can be applied to parks

and protected areas, especially parks near large urban centers where a break from loud,

man-made noise is most needed.

132

References
















2846. https://doi.org/10.1121/1.3493436





133






1295. https://doi.org/10.1007/s10980-011-9646-7




https://doi.org/10.1177/0013916512454430



https://doi.org/10.1089/eco.2014.0028










134


https://doi.org/10.1080/01490400701756436




















https://doi.org/10.1037/0003-066X.35.3.231

135



252–262.











https://doi.org/10.1121/1.417102



11(6), 305–313. https://doi.org/10.1890/120183






136


4), 349–362. https://doi.org/10.1080/01490400290050790



349–362. https://doi.org/10.1080/01490400290050790





Association.







283–295. https://doi.org/10.1080/01490400290050745





24(3), 369–381.

137



https://doi.org/10.1016/0272-4944(95)90001-2



https://doi.org/02724944/95/030169+14§12.00/0





Review of Research.












138





242. https://doi.org/10.1080/089419299279713





Framework for Managing the Carrying Capacity of National Parks. Joumal of Park

and Recreation Administration, 19(1), 93–108.



36(4), 557–579.




https://doi.org/10.1080/01490400.2011.550224




https://doi.org/10.1186/s12940-015-0006-y

139











6(3), 257–265. https://doi.org/10.1111/2041-210X.12330





https://doi.org/10.3397/1.599294





https://doi.org/10.1007/s13398-014-0173-7.2

140












121.











141



9224-1






https://doi.org/10.1121/1.4929934











https://doi.org/10.1080/01490400.2011.564924



142

https://doi.org/10.1080/01441640902827623












https://doi.org/10.1177/0013164404264117






https://doi.org/10.1121/1.3531803




143







Resources, 8(4), 351–30.






https://doi.org/10.3390/su9112088

Vaske, J. J., & Donnelly, M. P. (2002). Visitor Crowding and Normative Tolerances at

Congested Areas of Rocky Mountain National Park Xinran Lehto Assistant

Professor Department of Natural Resource Recreation and Tourism Human

Dimensions in Natural Resources Unit Colorado State University, (May).


Human Responses to Simulated Motorized Noise in National Parks. Leisure

Sciences, 36(February 2015), 251–267.

https://doi.org/10.1080/01490400.2014.888022

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Chapter 5

Conclusion and Implications

The purpose of this dissertation was to explore different methodologies for measuring

visitor experiences with the acoustic environment in National Parks. The first paper assessed the

relationship between one’s home sound level and their interpretation of soundscapes at Muir

Woods National Monument. The second paper utilized a large suite of sound clips to estimate

visitors’ threshold for propeller aircraft noise at Denali National Park and Preserve. And the third

paper analyzed tradeoffs visitors to Muir Woods National Monument are willing to make in order

to experience a more natural soundscape. This final chapter will summarize the findings from

earlier chapters and interpret the overall management implications of this dissertation.

Summary of Findings and Implications

This dissertation contains three independent manuscripts related to understanding and

measuring soundscapes in relation to visitor experience. Six separate research questions were

examined. This section will summarize the results and implications related to each question.


National Monument?

A multiple linear regression model was used to determine variables that relate to

visitors’ perception of the soundscape in Muir Woods National Monument. The

dependent variable, pleasantness, was used to measure overall interpretation of the sound

condition at the park. Results from the regression analysis determined factors related to

soundscape pleasantness included: the ability to hear natural sounds during the park visit,

sensitivity to noise, and the mean sound level of the respondents’ home zip code.

145



Spatial analysis tools were used to derive the average sound level of survey

respondents’ home zip code. The multiple regression model mentioned above suggest the

sound level of individuals’ home zip code significantly contributes to visitors’ perception

of the pleasantness of the parks’ soundscape. The model revealed a negative relationship;

meaning that as the mean sound level of the zip code increased, the rating of soundscape

pleasantness decreased.

Q3: How can researchers best inform the development of thresholds for soundscape

quality using dose response methodology?

To better control for noise exposure, survey respondents in the field listened to five audio

clips of varying levels of propeller aircraft, chosen randomly from a suite of 36 clips. The method

of randomizing the order and level of the audio clips improved the validity of visitors’ response to

noise. General linear mixed models were used to predict visitors’ response to the varying levels of

propeller aircraft noise. The models were able to account for random effects and other variables

that contributed to the final models. This methodology provided a more rigorous and accurate

understanding of anthropogenic sound sources that relate to thresholds for noise exposure.


Results from generalized mixed linear models showed that visitors’ response to

sound depends largely on the loudness of specific noise sources. Sound level (LAeq30s)

was an important factor in all four regression models. Clip sequence, or the order in

which audio clips were played was another important factor in predictive models which

further justifies the importance of playing a random order of varying levels of audio clips.

146

Q5: What tradeoffs are visitors willing to make in order to hear natural sounds in


The stated choice survey did not yield any clear tradeoffs related to soundscape

management. However, our results did indicate strong, positive preferences for direct

management strategies in the form of educational signs. Our study findings suggest that

visitors have a higher preference for experiencing a park with signs asking visitors to be

quiet, than a park with no soundscape management.

Q6: Are preferences different for visitors in the treatment group (signs present

asking visitors to maintain quiet) vs. the control group (all signs are covered)?

Our study yielded significant differences in management strategies between

treatment and control groups. The treatment group had a stronger preference for attributes

that aimed to quiet park visitors using educational signs and ranger presence. The

difference between groups could be a result of the treatment’s effectiveness in quieting

visitors. We can assume based on empirical evidence that the park was quieter during

treatment periods. Thus, the presence of educational signs increased visitors’ preference

for a quieter soundscape and the presence of indirect management such as signs.

Implications

The three separate studies presented in this dissertation explore different and innovative

methodological approaches to understanding soundscapes. While these studies were conducted at

either Denali National Park and Preserve or Muir Woods National Monument, management

implications can be applied to similar parks. The findings from these studies provide park

147

managers with a holistic approach to protecting soundscapes for the purpose of positive visitor

experiences.

Home Sound Level Influences Soundscape Perception

The findings from the second chapter of this dissertation suggest the level of sound

people are exposed to in their home environment contributes to their perception of the park

soundscape. While these findings don’t have a specific impact on soundscape management, they

do contribute to the existing body of social science literature that examines human response to

sound. Factors other than attitudes, beliefs, and values can play in important role in the variability

of individuals’ response to sound.

Our results do suggest the importance of quieting frontcountry parks similar to Muir

Woods National Monument. It’s possible that respondents in our study from louder areas found

the soundscape at Muir Woods to be less pleasant as a result of increased noise levels. For park

visitors to receive potential benefits of natural sound, an effort towards quieting frontcountry

parks is suggested.

Assessing Large Variety of Sound Levels Improves Validity of Soundscape Thresholds

Previous studies have used a small range of audio clips and average ratings of annoyance

to measure visitor thresholds for anthropogenic sound sources. The third chapter of this

dissertation identified potential thresholds for propeller aircraft using a large suite of varying

audio clips. Additionally, regression models that accounted for variability amongst individuals

was used to predict sound levels that were deemed annoying or unacceptable. This study was

148

conducted in Denali National Park and Preserve’s frontcountry area, but this method can be

applied to other parks and protected areas where anthropogenic noise is of concern.

Park Visitors Prefer Soundscape Management

The fourth chapter of this dissertation identified visitor preferences for soundscape

management at Muir Woods National Monument. Overall, visitors preferred forms of indirect

soundscape management in the form of educational signs. We also compared scores between the

treatment and control groups. Because visitors in the group that were exposed to signs had

significantly higher utility ratings for attributes with educational signs, it’s possible that this

group experienced the benefits of signs (i.e. a quieter park). Other parks and protected areas

where visitor caused noise is prevalent can use these findings to empirically justify the need for

educational signs that aim to quiet visitors.

Conclusion

Together, the three studies presented in this dissertation aimed to explore different

methodologies for measuring visitor experiences with the acoustic environment in National Parks.

While the methods used in these studies were innovative and will be useful to park managers, the

ultimate take away is that natural sounds are important. Results from the first study indicate that

visitors’ home sound level does in fact influence their perception of the park soundscape. In the

second study, potential thresholds for aircraft overflights were measured. Again, sound level was

an important factor in regression models. In the final study, we found that visitors prefer

soundscape management and educational signs that aim to quiet the park. These findings

highlight the value that visitors are placing on protecting natural sound conditions. In conclusion,

149

the simple vibration of sound, is an important part of the national park experience. Both park

managers and social scientists should continue to understand the human experience in relation to

soundscapes so that future generations can enjoy the benefits of natural sound.

Appendix A

Chapter’s 2 &4 Survey Instrument

Muir Woods National Monument

Visitor Study (A)

Park Permit Number: MUWO-2016-SCI-0001

Survey Information and Instructions:

The focus of this study is to better understand visitor preferences regarding the management of soundscapes within Muir

Woods National Monument

Your participation in the study is voluntary. There are no penalties for not answering some or all questions, but because

each participant will represent many others who will not be included in the study, your input is extremely important. The answers

you provide will remain anonymous. Our results will be summarized so that the answers you provide cannot be associated with

you or anyone in your group or household.

Pennsylvania State University thanks you for your assistance.

We estimate that it will take about 10 minutes to complete and return this questionnaire. You may send comments concerning the burden estimates

or any aspect of this information collection to: Dr. Peter Newman, Department Head & Professor, Recreation, Park and Tourism Management, 801

Ford Building, University Park, PA 16802, Penn State University, 814-863-7849 (phone) or [email protected] (email).

151

1. Visitors have different reasons for visiting Muir Woods National Monument. Please rate the importance

of each of the following reasons for your visit to Muir Woods National Monument today. Please mark

only one response for each item. Importance… Not

Relevant

Not at all

Important

Slightly

Important

Moderately

Important

Very

Important

Extremely

Important

To experience a sense of connection

with nature □ □ □ □ □ □

To experience the diversity of the

natural world □ □ □ □ □ □

To enjoy the natural quiet and sounds

of nature □ □ □ □ □ □

To give my mind a rest □ □ □ □ □ □

To get away from the usual demands

of life □ □ □ □ □ □

To get away from the noise back

home □ □ □ □ □ □

To develop your skills and abilities □ □ □ □ □ □

To improve your skills □ □ □ □ □ □

To do something with your family □ □ □ □ □ □

To be with friends □ □ □ □ □ □

To experience wildlife in nature □ □ □ □ □ □

To photograph wildlife □ □ □ □ □ □

Seeing the redwoods □ □ □ □ □ □

Appreciating the scenic beauty □ □ □ □ □ □

Experiencing solitude □ □ □ □ □ □

Getting some exercise □ □ □ □ □ □

Learning about nature □ □ □ □ □ □

Enjoying the peace and quiet □ □ □ □ □ □

Hearing the sounds of nature □ □ □ □ □ □

152

2. Based on your experience today, about how many different types of birds would you say are in the trail

corridor? Please mark one response.

□ 0-3 different types of birds




□ More than 15 different types of birds

3. If you heard bird song today, how would you rate the diversity of the bird song chorus? Please mark one

response.

Not at All

Diverse

A Little

Diverse

Moderately

Diverse

Highly

Diverse

Extremely

Diverse I did not hear bird song

□ □ □ □ □ □

153

4. Visitors hear a lot of sounds, including natural sounds and human-made sounds. Based on your experience

today, how would you rate the pleasantness of the soundscape? Please mark one response.

Very

Unpleasant

Moderately

Unpleasant

Slightly

Unpleasant

Slightly

Pleasant

Moderately

Pleasant

Very

Pleasant

□ □ □ □ □ □

5. Based on your experience today, how well were you able to hear natural sounds? Please mark one response.

□ Almost always clearly without interference from human-made sound

□ Usually clearly without interference from human-made sound

□ Sometimes clearly without interference from human-made sound

□ Usually with interference from human-made sound

□ Almost always with interference from human-made sound

154

In this section we would like know your opinion about a series of hypothetical management scenarios within Muir

Woods National Monument. There are 8 questions and each question has two scenarios. Please read both scenarios

and then select the one that you would most prefer to experience during a visit to the Muir Woods National

Monument.

6a. Which description below would best depict your most preferred experience in Muir Woods National

Monument?

☐ Scenario 1

☐ Scenario 2

■ You can hear natural sounds (e.g. birdsong, small

mammals) some of the time (about 25% of the

time)

■ You can rarely hear natural sounds (e.g. birdsong, small

mammals) (about 5% of the time)

■ Signs are posted along the trail educating visitors

about natural quiet & asking visitors to limit noise

■ Signs are posted along the trail educating visitors about

natural quiet

■ Trails are closed for one hour after dawn & one

hour before evening for the breeding bird chorus

■ Trails are open during operating hours

155

6b. Which description below would best depict your most preferred experience in Muir Woods

National Monument?

☐ Scenario 1

☐ Scenario 2

■ You can hear natural sounds (e.g. birdsong,

small mammals) most of the time (about 75%

of the time)


small mammals) some of the time (about 25%

of the time)

■ No signs are posted along the trail about natural

quiet

■ Signs are posted along the trail educating

visitors about natural quiet & asking visitors

to limit noise, and rangers are stationed along

the trail to limit visitor caused noise

■ Trails are closed for one hour after dawn for the


■ Trails are open during operating hours

156

6c. Which description below would best depict your most preferred experience in Muir Woods

National Monument?

☐ Scenario 1

☐ Scenario 2



of the time)


small mammals) about half of the time (about

50% of the time)


visitors about natural quiet & asking visitors to

limit noise



to limit noise, and rangers are enforcing

visitors to limit their noise along the trail



■ Trails are closed for one hour after dawn &

one hour before evening for the breeding bird

chorus

157

6d. Which description below would best depict your most preferred experience in Muir Woods

National Monument?

☐ Scenario 1

☐ Scenario 2

■ You can rarely hear natural sounds (e.g.

birdsong, small mammals) (about 5% of the

time)



of the time)


quiet



to limit noise, and rangers are enforcing

visitors to limit their noise along the trail

■ Trails are open during operating hours ■ Trails are open during operating hours

158

6e. Which description below would best depict your most preferred experience in Muir Woods

National Monument?

☐ Scenario 1

☐ Scenario 2



time)



time)



limit noise, and rangers are enforcing visitors to

limit their noise along the trail







■ Trails are closed for one hour after dawn for

the morning breeding bird chorus

159

6f. Which description below would best depict your most preferred experience in Muir Woods

National Monument?

☐ Scenario 1

☐ Scenario 2



of the time)



of the time)


visitors about natural quiet





■ Trails are closed for one hour after dawn & one

hour before evening for the breeding bird

chorus



160

6g. Which description below would best depict your most preferred experience in Muir Woods

National Monument?

☐ Scenario 1

☐ Scenario 2



50% of the time)



50% of the time)



limit noise, and rangers are enforcing visitors to

limit their noise along the trail

■ No signs are posted along the trail about

natural quiet

■ Trails are open during operating hours ■ Trails are closed for one hour after dawn for


161

6h. Which description below would best depict your most preferred experience in Muir Woods

National Monument?

☐ Scenario 1

☐ Scenario 2



50% of the time)



of the time)


quiet



to limit noise





162

7. The following list suggests kinds of reasons you might have deliberately chosen to limit the amount of noise

you made in the park. For each of the reasons below, please indicate the extent to which you agree or disagree

that the reason applies to you. Please mark only one response for each item.

Strongly

disagree

Disagree Neutral Agree Strongly

agree

I was afraid I would be reprimanded if I made too

much noise. □ □ □ □ □

I was afraid I would be fined if I made too much

noise. □ □ □ □

I was afraid other members of my group would

think poorly of me if I made too much noise. □ □ □ □ □

I was afraid other visitors in general would think

poorly of me if I made too much noise. □ □ □ □ □

It’s not fair to other visitors for me to make a lot of

noise. □ □ □ □ □

I feel better about myself when limiting the amount

of noise I make. □ □ □ □ □

8. Which of the following best describes where you went in Muir Woods today? Please mark one response.

□I only walked on the paved/boardwalk trails on the canyon floor.

□I walked on the paved/boardwalk trail on the canyon floor and hiked on some of the

unpaved trails on the slopes of the canyon.

163

9. Please check the box corresponding with how well you agree or disagree. Please mark only one response for

each item.

Strongly

Disagree

Disagree Slightly

Disagree

Slightly

Agree

Agree Strongly

Agree

I am sensitive to noise.

□ □ □ □ □ □

I find it hard to relax in a place that's noisy. □ □ □ □ □ □

I get mad at people who make noise that

keeps me from falling asleep or getting

work done.

□ □ □ □ □ □

I get annoyed when my neighbors are noisy. □ □ □ □ □ □

I get used to most noises without much

difficulty. □ □ □ □ □ □

10. How crowded did you feel on the trail today? Please select one number.

1 2 3 4 5 6 7 8 9

Not crowded at all Slightly crowded Moderately crowded Extremely crowded

11. Including this visit, how many times have you visited Muir Woods National Monument?

Approximate number of visits: _____________

12. Approximately how many hours did you spend in Muir Woods National Monument today?

Approximately _____________hours

164

13. How many adults and how many children were in your personal group (spouse, family, friends) during this

trip to Muir Woods National Monument today? Please provide a number.

# of Adults (Age 16 or older) _______ # of Children (Age 15 or younger) _______

14. How would you describe your group?

□ Alone

□ Family

□ Friends

□ Family and Friends

□ Organized Group (e.g., club, educational group)

□ Commercial tour group

□ Other (Please specify):______________________

15. What is your gender?

Male Female

16. In what year were you born?

Year Born: __________________

17. Do you live in the United States?

Yes (What is your zip code? __________)

No (What country do you live in? ______________________________

165

18. What is the highest level of formal education you have completed? Please mark only one response. Some high school

High school graduate or GED

Some college, business or trade school

College, business or trade school graduate

Some graduate school

Master’s, doctoral or professional degree

Thank you for your assistance in completing this survey.

Start here

Appendix B

Chapter 3 Survey Instrument

Denali National Park and Preserve

Visitor Study B

Sound Clip Survey

PAPERWORK REDUCTION ACT STATEMENT: The National Park Service is authorized by the NPS

Research Mandate (54 USC 100702) to collect this information. This information will be used by park

managers to understand visitors’ perceptions of sounds in the front-country of Denali National Park and

Preserve. Responses to this request are voluntary and anonymous. Your name will never be associated with

your answers, and all contact information will be destroyed when the data collection is concluded. No action

may be taken against you for refusing to supply the information requested. An agency may not conduct or

sponsor, and a person is not required to respond to, a collection of information unless it displays a currently

valid OMB control number and expiration date.

BURDEN ESTIMATE statement: Public reporting burden for this form is estimated to average 15 minutes

per response. Direct comments regarding the burden estimate or any other aspect of this form to: Denali

National Park and Preserve, PO Box 9, Denali Park, AK 99755.

167

1. Is this your first visit to Denali?

YES ☐ (If YES, move on to #2) NO ☐

If NO, Approximately how many times have you visited Denali?

Times before ___________ (approximate)

OR

☐ Don’t know/not sure

2. How important was it that these visits to Denali’s developed area or front country provide you with

the opportunity to...? Mark "Not relevant" if an aspect was not relevant for this visit.

Importance

Not

Relevant

(0)

Not at all

Important

(1)

Slightly

Important

(2)

Moderately

Important

(3)

Very

Important

(4)

Extremely

Important

(5)

Appreciate the history and

cultural significance of the site (0) (1) (2) (3) (4) (5)

View the natural scenery (0) (1) (2) (3) (4) (5)

Experience a feeling of

calmness, peace, or tranquility (0) (1) (2) (3) (4) (5)

Experience a sense of adventure

or challenge (0) (1) (2) (3) (4) (5)

Enjoy the natural quiet and

sounds of nature (0) (1) (2) (3) (4) (5)

168

3. How much did man-made sounds interfere with your enjoyment during your time in Denali’ front

country? (Please select one)

Much less than

I expected

Less than I

expected

About as much as I

expected

More than I

expected

Much more than

I expected

1 2 3 4 5

4. What man-made sounds interfered the most with your enjoyment? (Please describe)

___________________________________________________________________

5. Instructions

For the next set of questions, we would like you to listen to five short recordings of sounds that are typically

heard in Denali’s front-country.

Please place the headphones on your head. We will ask you to listen to five brief recordings of sounds. As you

listen to each recording, imagine how you would have felt if you had heard the sounds in the recording during

your visit to Denali’s front country (only).

The survey administrator will play each sound clip for you. Please listen to each recording in its entirety; then

answer the survey questions that relate to each recording.

169

RECORDING #1

6. How acceptable or unacceptable would the aircraft sounds in recording #1 have been if you had

heard them during this visit to Denali while in the front country?

Unacceptable Acceptable

Extremely Very Moderately Slightly Neutral Slightly Moderately Very Extremely

(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

7. How pleased or annoyed would you have been by aircraft sounds in recording #1 if you had heard

them during this visit to Denali while in the front country?

Annoyed Pleased


(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

Pause: Keep your headphones on and wait for the survey administrator to play recording #2

RECORDING #2





(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

170



Annoyed Pleased


(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)


RECORDING #3





(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)


them during this visit Denali while in the front country?

Annoyed Pleased


(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)


171

RECORDING #4





(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)



Annoyed Pleased


(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)


RECORDING #5





(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

172

15. How pleased or annoyed would you have been by aircraft sounds in recording #5 if you had heard them

during this visit to Denali while in the front country?

Annoyed Pleased


(-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

Instructions: Now we would like to know how often you think it’s acceptable to hear aircraft sounds while in

Denali’s front-country. Please listen to a short recording of both natural and aircraft sounds, and then answer

the questions that follow.

RECORDING #6

16. How acceptable or unacceptable would the aircraft sound in recording #6 be if it occurred for the

following amounts of time per hour during your time in Denali’s front country? Provide an answer

for each time period.


Minutes

Per

Hour

Extremely

(-4)

Very

(-3)

Moderately

(-2)

Slightly

(-1)

Neutral

(0)

Slightly

(+1)

Moderately

(+2)

Very

(+3)

Extremely

(+4)

3 (-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

9 (-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

15 (-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

30 (-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

173

17. How frequently would you prefer to hear small airplanes as you heard in recording #6 while in

Denali’s front country? Please enter a number or select the checkbox.

No more than ______ small airplanes in an hour

OR

☐ I would prefer to never hear small airplanes

18. How acceptable or unacceptable would the aircraft sounds in recording #6 be if you heard it the

following number of times per day during your time in Denali’s front country? Provide an answer

for each number.


Flights

per day

Extremely

(-4)

Very

(-3)

Moderately

(-2)

Slightly

(-1)

Neutral

(0)

Slightly

(+1)

Moderately

(+2)

Very

(+3)

Extremely

(+4)

1 (-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

10 (-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

25 (-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

50 (-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

100 (-4) (-3) (-2) (-1) (0) (+1) (+2) (+3) (+4)

19. How frequently could you hear small airplanes as you heard in recording #6 before you would no

longer visit Denali’s front country? Please enter a number or select the checkbox.

No more than ______ overflights in a day.

OR

I would visit Denali’s front-country regardless of how frequently small airplanes or helicopters are

heard.

174

20. Besides the recordings you just listened to, did you HEAR aircraft during your time in Denali?

☐ Yes (If yes move on to #21)

☐ No (If no, move on to #22)

21. During this visit to Denali how much did noise from aircraft annoy you?

Annoy

Not at all Slightly Moderately Very Extremely

☐ ☐ ☐ ☐ ☐

22. Have you ever taken a commercial flightseeing tour over Denali or any other park? Please check all

that apply.

YES, I have taken a commercial flightseeing tour over Denali ☐

YES, I have taken a commercial flightseeing tour over another

park ☐

NO, I have never taken a commercial flightseeing tour over a

park ☐

23. Are you interested in taking a commercial flightseeing tour over Denali?

☐ YES ☐ NO ☐ Don’t Know/Not Sure

175

24. Have you ever taken an air taxi over Denali or any other park? Please check all that apply.

YES, I have taken an air taxi over Denali ☐

YES, I have taken an air taxi over another park ☐

NO, I have never taken an air taxi over a park ☐

25. On this trip, did you and your personal group camp inside Denali?

YES

If yes, where did you camp? _____________________________________

NO, day use only

26. How many adults and how many children were in your personal group (spouse, family, friends)

during this visit to Denali? Please provide a number.

Number of Adults (Age 16 or Older) _______

Number of Children (Age 15 or Younger) _______

27. On this visit, how long did you and your personal group stay at Denali? Please list hours or days

below.

Number of hours, if less than 24 _______

or

Number of days, if 24 hours or more _______

28. Were you or your personal group part of some larger commercial, educational, or other organized

group of visitors? ☐ YES ☐ NO

176

29. What is your gender? ☐ Female Male

30. In what year were you born? Year born:___________

31. Do you live in the United States?

YES (What is your zip code? __________)

NO (What country do you live in? ______________________________)

32. What is the highest level of formal education you have completed? (Check one.)

Some high school (6)

High school graduate or GED (5)

Some college, business or trade school (4)

College, business or trade school graduate (3)

Some graduate school (2)

Master’s, doctoral or professional degree (1)

33. Are you Hispanic or Latino? ☐ YES ☐ NO

34. What is your race? (Check all that apply.)

American Indian or Alaska Native (6)

Asian (5)

Black or African American (4)

Native Hawaiian (3)

Pacific Islander other than Native Hawaiian (2)

White (1)

Denali National Park and Preserve and Penn State University both thank you for your assistance.

VITA

Lauren Abbott Ferguson EDUCATION

Ph.D. 2018 The Pennsylvania State University, University Park, Pennsylvania

Recreation, Park, and Tourism Management

Human Dimensions of Natural Resources and the Environment (Dual-Degree)

M.S. 2015 The Pennsylvania State University, University Park, Pennsylvania

Recreation, Park, and Tourism Management

Thesis Title: The Influence of Natural Sounds on Attention Restoration

B.S. 2008 Colorado State University, Fort Collins, Colorado

Natural Resource Recreation and Tourism

Environmental Communication Concentration

SELECTED PUBLICATIONS

Francis, C. D., Newman, P., Taff B. D., Crow, W., Monz, C. A., Levenhagen, M., Petrelli, A. R.,

Abbott, C. L., Newton, J., Burson, S., Cooper, C. B., Fristrup, K. M., McClure, C. J. W.,

Mennitt, D., Giamellaro, & M., Barber, J. R. (2017). Acoustic Environments Matter:

Synergistic Benefits to Humans and Wildlife. Ecology Letters.

Abbott, C. L., Taff, B. D., Newman, P., Benfield, A. B., & Mowen, A. J. (2016). The Influence

of Natural Sounds on Attention Restoration. Journal of Park and Recreation

Administration 34(3), 5-15. DOI: 10.18666/JPRA-2016-V34-I3-6893

Abbott, C. L., Taff, B. D., Newman, P, & Burson, S. (2016). Exploring Vertical Wilderness in

the Acoustic Environment. Submitted to National Park Service, Washington D.C.

SELECTED CONFERENCE PRESENTATIONS

Abbott, C.L., Newman, P., Taff, B.D., Burson, S. (2017, April). The effects of natural and

anthropogenic sounds on climber experiences in Grand Teton National Park.

Presented at the meeting of the 19th annual George Wright Society Conference,

Norfolk, VA.

Abbott, L.C., Newman, P., Taff, B.D., & Blanford, J. (2016, November). Understanding

soundscape perceptions in national parks, Presented at Penn State GIS Day, University

Park, PA.

Abbott, C. L., Newman, P., Taff, B. D., Burson, S. (2016, October). Exploring Vertical

Wilderness in the Acoustic Environment. Presented at the meeting of the 13th annual

Biennial Scientific Conference on the Greater Yellowstone Ecosystem, Jackson, WY.

TEACHING EXPERIENCE

2017 Instructor- Research and Evaluation in Recreation and Parks (RPTM 433), The

Pennsylvania State University

2018 Instructor- Grantsmanship, Eval, & Research Methods (RMP 724), University of

New Hampshire

Documents

STRATEGIES FOR MANAGING NATURAL SOUNDS FOR HUMAN