Acoustic Evaluation Method Taiwan

ARTICLE IN PRESS

0360-1323/$ - se

doi:10.1016/j.bu

�Correspondfax: +886 4 228

E-mail addr

Building and Environment 43 (2008) 1619–1632

www.elsevier.com/locate/buildenv

Acoustical environment evaluation of Joint Classrooms for elementaryschools in Taiwan

Che-Ming Chianga, Chi-Ming Laib,�

aDepartment of Architecture, National Cheng-Kung University, TaiwanbGraduate Institute of Rural Planning, National Chung-Hsing University, 250, Kuo-Kuang Road, Taichung City 402, Taiwan

Received 14 February 2007; received in revised form 10 October 2007; accepted 12 October 2007

Abstract

As open education is the future education mainstream, Joint Classrooms are found in new schools or rebuilt old schoolhouses inTaiwan. However, there have been serious problems in acoustic environment in the Joint Classrooms in the 6 years since the first

appearance in 1999. There are no substantial evaluations or improvement suggestions available now. As a result, the acousticenvironments of Joint Classrooms in Taiwan were analyzed, via on-site measurements and questionnaires, to understand the currentsituation of acoustic environment and compare the differences between traditional and Joint Classrooms.This study proposed an Evaluation Model of Acoustic Environment in Classrooms to evaluate the environmental quality of

elementary schools with actual measurements and questionnaires. It was found that the acoustic environment of these elementary schoolsis not adequate. With open windows, the noise levels at both Joint Classrooms and traditional classrooms are 20 dB (A) above thestandard. The reverberation time in traditional classrooms is better, while in Joint Classrooms it tends to be longer.

r 2007 Elsevier Ltd. All rights reserved.

Keywords: Acoustic; Classroom; Elementary school; Noise; Reverberation

1. Introduction

Open education is the current and future trend. Bothnew schools and rebuilt schoolhouses adopt the designof Joint Classrooms (JC). Since 1999, people haveheld different viewpoints on the practice and adaptabilityof this new style of classroom. Serious problems arefound in the acoustic environment inside the JointClassrooms. There are no substantial evaluations orimprovement suggestions available now. One shouldnot ignore the impact of the school environment onchildren, since they spend about one-third of their day atschool. Their hearing, learning, and physical and mentalhealth will be affected if they are in an inappropriateenvironment for a long time. This study conductedinvestigations and discussion on acoustic environment

e front matter r 2007 Elsevier Ltd. All rights reserved.

ildenv.2007.10.014

ing author. Tel.: +886 4 22840513x108;

78988.

ess: [email protected] (C.-M. Lai).

inside the Joint Classrooms and understanding thecharacteristics of the acoustic environment of differentlayout styles in the classrooms in order to meet thefollowing goals:

(1)
understanding the current situation of acoustic envir-onment in the Joint Classrooms;
(2)
understanding the differences between the acousticenvironment of Joint Classrooms and traditionalclassrooms;
(3)
understanding the differences of acoustic environmentbetween different layout styles of Joint Classrooms.
With reference to acoustic environment evaluationfactors and standards at home and abroad, this studyproposed an Evaluation Model of Acoustic Environmentin Classrooms to evaluate the environmental qualityof elementary schools with actual measurements andquestionnaires.

www.elsevier.com/locate/buildenv

dx.doi.org/10.1016/j.buildenv.2007.10.014

mailto:[email protected]

ARTICLE IN PRESSC.-M. Chiang, C.-M. Lai / Building and Environment 43 (2008) 1619–16321620

2. Background

Planning of school buildings based on education philo-sophy, school environment, and building conditions withconsideration to people, space, time, and budget so thatschool land, schoolhouses, campuses, and affiliated facilitiescan be arranged in harmony. The changes in teaching andlearning directly affect people and schoolhouses. The spacewhere education takes place also transforms with the changeof education methods in different times.

2.1. Development and transformation of educational styles

The traditional thinking in Taiwan is based on adults(teachers, parents) making educational decisions with the useof entrance examinations and diplomas. Information wassupplied and students’ memories tested with emphasis on thedivision of subjects. Adults designed teaching materials forchildren. Teaching emphasized results more than process andthe focus of the entire teaching system was on how theteacher taught. As teaching focused on the content of thepaper, teaching was mostly conducted in classrooms whereteachers taught and students memorized. The stuffingprocess and military administration made it important forstudents to be arranged in rows in classrooms. There was astudent in each position to manage the presence of thestudents and supervise the students’ performances. With thesame dimensions and elevations of desks and chairs, someteachers arranged seating based on the height of students.Other teachers arranged the seating based on students’performances in various tasks and academic achievements inexaminations. They supervised, sorted, and encouragedstudents in the space designed for education.

The concept of open education is to oppose and reformthe old, traditional, and rigid education. Open educationfirst appeared as the so-called informal education in the UK,which was later popular in the US and then spread to therest of the world. Education is the unique spiritual activityof mankind and the purpose of education is to teach aperson, as a person, to be a person with individuality and asense of mission. Education should help people develop thecapability to live with others in harmony and be people whoexperience self-growth. The courses aim to give childrenqualities of democracy and self-control. Therefore, courses,teaching materials, schedules, and learning time are quiteflexible. Qualitative assessment is used for the learningperformance and the learning environment is set up toprovide children with a liberal and appropriate environ-ment, encouraging children to express their learningattitudes. Children in open classrooms are free but not leftalone. They are the center of learning, while teachers onlybecome involved when required.

2.2. Evolution of classroom space

For a long time, quality and quantity of elementaryschools in Taiwan were completely in accordance with the

Standards of School Building Facilities set by the Ministryof Education. The unit of measure for every regularclassroom in elementary schools was 7.5m� 9.0m withthe square measure of 67.5m2 for each classroomand a 2.5-m-wide corridor. If the values, educationphilosophy, and demands of teachers and students inour society did not change so fast, maybe the traditionalclassroom plan could still be applied today. Beginning inthe mid 1980s, however, after the lift of martial law,Taiwan had been seeing a call for educational reform.New educational policies, methods, and teaching materialswere booming, creating tremendous pressure on thetraditional school building space. The basic educationalconcepts include the individualization of studentsand unique issues. Urban communities are asking schoolsfor access to the campus and facilities. Teachingbecomes vivid, diverse, and energetic with outdoor teach-ing, media teaching, and team teaching, etc. The sub-stantial changes in education lead to transformation ofschool buildings [1].There is a close relationship between space and people.

In the traditional closed-in classrooms, there lacks inter-action between people and teaching, causing isolation ofclasses. Large, flexible, and common space accommodatesmany classes at the same time, with movable walls orshields for flexible spatial separation. Creative and diversecourses, along with flexible space situations, and a teachingphilosophy based on students, are benefits of a large classteaching model.Undoubtedly, narration teaching in traditional class-

rooms reflects traditional teaching. Teaching activitiesand teaching methods are actually closely connected.On the one hand, teaching activity styles reflect thenew trend in teaching methods; on the other hand, newteaching activity styles are developed with new teachingmethods. Stimulated by the new education philosophy, inaddition to narration teaching, traditional class teachinghas now emphasized the importance of teaching aidsand media [2]. Traditional classrooms are unable tomeet the diversity of teaching activities today. They lackspace for children during the recess breaks and fornecessary activities. They are inconvenient and insufficient.The redefinition of classroom functions providesmulti-purpose space (MPS) including: classroom space, alarge work space, a Joint Classroom learning resourcecenter, a Joint Classroom layout, a display space, space fordiverse activities for children, work space for teachers, etc.Overall, as traditional class teaching space has to bemaintained, the regular classrooms are expanded tobecome self-contained classrooms to support teachers andstudents with the space functions that all teaching activitiesrequire [3].As changes of the education essence, Joint Classrooms

are the trend in the recent years in school buildings. TheJoint Classrooms refer to a large unit teachingspace containing two to four regular classrooms, with anMPS offering teachers and students a more functional

ARTICLE IN PRESS

RegularClassroom

MPS

MPS

RegularClassroom

Joint Classroom

Fig. 1. Spatial layout of Joint Classrooms.

C.-M. Chiang, C.-M. Lai / Building and Environment 43 (2008) 1619–1632 1621

education space as in Fig. 1. The space details andfunctions are:

(1)
Joint Classrooms: Joint Classrooms connect two to fourclassrooms together into a group. In this group, eachclass has its individual classroom as well as MPS (alsocalled team teaching space). Such a design enables eachclass to have its own space and to share a larger spaceand resources. This design makes team teaching moreaccessible and provides space for teaching diversity.The classrooms can be separated with shields or shortcabinets for flexible use.
(2)
Multi-purpose space: A large empty space is availableon campus, where teachers and students can take partin team education, mixed-age education, theme ex-ploration, games, drama performances, and exhibi-tions, etc. The space has multi purposes based on thespatial layout for different activities or those who makeuse of the space.
2.3. Influence and harm of environmental noises at schools

Sounds that cause physical or mental unpleasantness,hinder talking, thinking, rest, and sleep are defined asnoise. People have individual reactions to sounds. Ingeneral, environmental noise for a certain target is thesound at the location, excluding the sound of the target.The spontaneous noise at schools is the internal fixedinterference factor and can be corrected by coursearrangement and activity allocation. External noise de-pends on where schools are. For example, the 12 highschools and elementary schools around Taiwan TaoyuanInternational Airport have 2/3 WECPNL (weightedequivalent continuous perceived noise level) exceeding70 dB (A) [4]. Similarly, schools around KaohsiungInternational Airport are suffering from serious aviationnoise. Schools beside overpasses or highways have toenhance their noise insulation facilities or even need tomove to new addresses if there is serious noise interference.

From animal experiments, it was found that younganimals, under exposure to a certain level of noise, sufferfrom more damaged inner ears than old animals. Mills [5]holds that children are more sensitive to noise than adults.Volumes that adults believe are safe may cause harm to

children. Influences of noise on teachers and students canbe divided into the following areas:

(1)
HealthNoise causes harmful mental and physical symp-
toms:– getting angry easily with declined concentration;– anxiety or nervousness;– reduced judgment capability;– getting tired easily with lower efficiency;– hyper function of hearts, dyspepsia, poor appetite,tense muscles, and slowed actions;

– insomnia, headache, tinnitus, and facial pallor;– occupational hoarseness of teachers.

(2)
Students’ learningAs children are not fully developed in language, they
are more sensitive to noise interfering in talking.Provided they are exposed to high noises for a longtime when they are learning speech, language, andlistening, their performances in reading and studyingwill be affected. Chronic exposure to low stimulatednoises tends to be ignored and, as time passes, willcause hearing loss. Mills [5] holds that children aremore sensitive to noises than adults, with possiblereasons being less recognition of environmental pres-sure and lack of preparation to face the pressure.Damage by noises during children’s early developmentand education may cause long-term effects. Otherimpacts include inability to concentrate, poor readingand thinking, and bad performance of students onassignments.

2.4. Issues of acoustical environment of Joint Classrooms

Xue [6] and Lin [2] used an apparatus to measure thelight environment and acoustic environment of classrooms.They measured Joint Classrooms at two schools in TaipeiCounty/City and Kaohsiung City. In acoustic environ-ments, they concluded that the noise level in JointClassrooms often exceeds 60 dB (A). From the survey in1991 in Taiwan, among the 577 elementary schools undersurvey, over 60.5% of traditional classrooms that close offthe sound sources had noise levels exceeding 60 dB (A) and11.3% of them over 70 dB (A). This indicates serious noise

ARTICLE IN PRESS

Fig. 3. Joint Classroom with individual style.

C.-M. Chiang, C.-M. Lai / Building and Environment 43 (2008) 1619–16321622

problem. The study then points towards outdoor noisesource and the neighboring classrooms. The sound inter-ference of Joint Classrooms may be because of theiropenness. From noise meter readings, class activities in thefive schools in the afternoon were found to have the highestvolume in a day. Noise level changes with course contentand teaching methods. Moreover, Zhang [7] analyzed thephysical environment of Joint Classrooms, exploringinterference and reasons for sound interference, soundinsulation effect, natural lighting, artificial illumination,and ventilation. She used questionnaires filled out byteachers and students to better understand the situation.From the returned questionnaires, it was found that bothteachers and students were suffering from serious soundinterference in classes. Teachers believe that the mainreason is inappropriate Joint Classroom design and lack ofpartitions or removable division plates.

3. Research method

3.1. Classrooms under investigation

The target includes Joint Classrooms at many elemen-tary schools in Kaohsiung City, located in the southernpart of Taiwan. Acoustic environment measurements andsurveys are taken at representative schools. At the moment,there are 99 public and private elementary schools inKaohsiung City and 76 of them have traditional class-rooms and 11 of them have Joint Classrooms. Among the11 schools, 9 are newly established ones. One can see JointClassrooms as the trend for new schools or rebuilding ofold schoolhouses in recent years.

Joint Classrooms in Kaohsiung City are divided by MPSand relevant location of classrooms into joint styles andindividual styles. The former has classrooms and an MPScombined into a large space as in Fig. 2, while the latter hasindividual Joint Classrooms and an MPS separated as inFig. 3. Spatial layout of Joint Classrooms can be dividedinto straight rows, squares, L-shapes, curves, and indivi-dual room straight rows, individual room L-shapes, andgeneral as in Table 1. In this study, Joint Classrooms withJoint Style were selected as our research targets, as shownin Table 2. Four traditional classrooms in the same place inKaohsiung City were also investigated for comparison. To

Fig. 2. Joint Classroom with Joint style.

understand the real physical environment of the class-rooms, the interior acoustic environment between Januaryand May 2005 when students had classes was investigated.On-site measurements and questionnaires were takensimultaneously.

3.2. Proposed Evaluation Model of Acoustic Environment in

Classrooms

(1)
Converting the measurement results into physicalevaluation
Building styles at elementary schools are becomingmore and more diverse. Post-occupation evaluation,for quality of the environment in classrooms of variousstyles, will help to demonstrate the performance ofbuildings in a short time period. In the longer term, itcan help in architectural design and school operation.In the long-term, it can build the database of designand establish standards for school buildings.

In schoolhouses, teachers and students spend most ofthe day in classrooms. Target and usage of schoolbuildings differ from other buildings. This study wishedto have an objective standard to evaluate the comfortand healthiness of the acoustic environment in schoolclassrooms. It was to be based on relevant researches,with reference to domestic and foreign interior acousticenvironments at schools, evaluation factors, andstandards. This study established an Evaluation Modelof Acoustic Environment in Classrooms: physicalaspect in the simple scoring.

According to Nihonjinron, Japan, the noise level is55dB (A) (windows opened) and 50dB (A) (windowsclosed) in school classrooms [8]. American NationalStandards Institute (ANSI) and WHO [9] suggestbackground noise in the classroom should be below35dB (A), 45dB (A) maximum in the rooms and 55dB(A) maximum on fields and in sports areas. CHPSprogram in the United States stipulates a 45dB (A)maximum in classrooms when there are no people inside.In many American communities, the outdoor noise is55dB (A) maximum [10]. Please refer to Table 3.

There are no relevant regulations on interior noiselevels in school rooms in Taiwan. In a survey made in

ARTICLE IN PRESS

Table 1

Categories of spatial layout of Joint Classrooms in Kaohsiung City

MPS

layout

Category Print No. of

schools

adopting

Explanations

Joint style Straight

row

2 In most cases, four classes are in a group. Classrooms are divided by removable

division plates. The MPS is at the entrance. The layout is long and narrow and

each class has its territory.

Square 1 Four classes are in a group with removable division plates or short cabinets

separating classrooms. This layout has similar length and width and is more

suitable for team teaching and activities.

L-shape 1 Four classes are in a group with removable division plates or short cabinets

separating classrooms. The MPS is in an L-shape. Owing to the shape, some

space is available for hardware for students and activities.

Curve 2 Two to three classes are in a group. Classrooms are separated by removable

division plates. When plates are open, classrooms are connected. The MPS is

inside the classrooms and the layout is opposite to the straight row. In

comparison, the MPS has higher completeness and each has its territory.

1 Three classes are in a group and the MPS is in the front. Spatial layout is

changeable. The balcony by the classrooms is where students wash hands and

clean.

Individual

style

Straight

row

3 Three to four classes are in a group and the layout is similar to the curved one.

The straight row is inside the classrooms. Walls with glass and doors separate

the classrooms. There are two individual spaces with one MPS and one

independent space.

L-shape 1 Four classes are in a group and the MPS is at the corner of each set of two

classrooms. Each classroom and the MPS are independent.


1991, among the 577 elementary schools under survey inTaiwan, over 60.5% of traditional closed classroomsexperienced sound sources with a level exceeding 60dB

(A) and 11.3% of them were over 70dB (A). Mostof the interference was traffic noise outside, playingsounds from the fields, and teaching from neighboring

ARTICLE IN PRESS

Table 2

Layout of the cases in this study

Category Straight row Round curve Square L-shape

Print

Table 3

Foreign standards governing interior acoustic environment

Country Standards, regulations or

guidelines

Sources

USA Classroom standard (not in use):

35 dB (A)

ANSI [8]

Classroom Guidelines: 45 dB (A) Huang [8]

WHO Guidelines: WHO [9]

Classrooms: 35 dB (A)

Rooms: 45 dB (A)

Fields, sports areas: 55 dB (A)

CHPS Classroom Guidelines: CHPS [10]

45 dB (A)

0.6 s reverberation (maximum)

Outdoors in communities: 55 dB

(A)

City of Los Angeles and

other areas [8]

Japan Classrooms with opened

windows: 50 dB (A)

Health Security

Program [8]

Classrooms with closed windows:

55 dB (A)

Table 4

Scoring of the acoustic environment in classrooms: physical aspect

Scoring 20 40 60 80 100

Leq (dB (A)) 470X 460X 450X 440X

|RT�0.6| (s) p0.3 p0.2 p0.1 p0


classrooms. Compared with the foreign regulations,we still need to improve. Proposed scoring in thisstudy is 55dB (A) (windows opened) as the passinggrade for interior noises and 10dB (A) as the scoringgap.

School classrooms require good verbal clarity andshould avoid echo interference. This study also includedreverberation time (RT) as one of the evaluation factors.Review of literature revealed that most countries usecriteria of 0.4–0.8 s reverberation for children’s class-rooms. CHPS [10] requires no longer than 0.6 s. LongRT in the room will cause insufficient verbal claritywhile short RT will make the sound in the room dry.Generally, the acoustical environment quality of class-rooms in elementary schools in Taiwan is poor. Relevantdomestic researches suggested: the classroom reverbera-tion criteria can be set as 0.8–1 s initially. Thus, afterbuilding renovation with little budgets, this goal can bereached easily. Then the criteria can be gradually movedto 0.6 s to achieve higher indoor acoustic quality. Toemphasize the importance of the hearing health ofchildren and learning efficiency with reference to theinternational classroom reverberation criteria, this studyused 0.6 s as the reverberation criterion, with the highest

score at 0.6 s (in five grades, the full score). More than0.8 s or less than 0.4 s is a failure. Suggested scoringmethod is shown in Table 4.

(2)
Converting the questionnaires results into mentalevaluation
This study converts the questionnaire evaluationof interviewed teachers in various types of classroomsinto scoring for comparisons. The questionnaireincludes choices and open questions. The former hasthree to five choices. Responses to three-choice ques-tions are converted to score 20, 60, and 100; those tofive-choice questions are converted to 20, 40, 60, 80,and 100.

(3)
Proposed comprehensive evaluation modelTo help compare physical and mental scorings of
various spaces, X-axis in Fig. 4 is converted into mentalscoring (as above). Y-axis represents the scoring ofphysical evaluation from the measurement results(Table 4). Both are combined into the EvaluationModel of Acoustic Environment in Classrooms.Physical scorings and mental scorings are divided intofour areas. The area with both physical and mentalscoring lower than 60 is an area for physical and mentaldiscussions. The area with both physical and mentalscoring higher than 60 is a passing area. The area withboth physical and mental scoring higher than 80 is theoptimum area. The area with mental scoring higherthan 60 but physical scoring lower than 60 is an areafor physical aspect discussions.

3.3. On-site survey

Based on the above evaluation model, on-site measure-ments were carried out. The spatial characteristicsincluding general condition of schoolhouses, number ofpeople in the rooms, classroom area (square measure),room volume, aperture ratio, and renovation materials

ARTICLE IN PRESSC.-M. Chiang, C.-M. Lai / Building and Environment 43 (2008) 1619–1632 1625

were also investigated. The measurement height is at thereading level of students, as much as possible. Testapparatus is listed in Table 5. Leq readings are recorded

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Mental evaluation

Phys

ical

eval

uatio

n

BEST

BETTER

Area for MentalAspect Discussion

Area for Physical andMental Discussions

Area for PhysicalAspect Discussion

Fig. 4. Evaluation Model of Acoustic Environment in Classrooms.

Table 5

Measurement location of acoustic environment and major apparatus

Item Location Apparatus

Leq

Sound receipt location

Noise meter

Sound

pressure

Sound reception

Sound source

Sound

source

Pink noise, am

and wave filter

Sound

reception

Microphone, a

recorder (recor

system)

RT

Sound receptionSound source

Sound

source

Signal gun, pow

amplifier

Sound

reception

Microphone, a

recorder (recor

system)

every 4min. A weighing is done for classroom soundpressure with fast movement characteristics:

(1)

plifie

nd

ding

er

nd

ding

Leq: The noise meter is placed at the center of theclassroom to measure the noise levels during the classhours and the recess breaks. During the class hour,when indoor noise is measured, measurement ofambient background noise of adjacent empty class-rooms is also conducted.

(2)
Sound pressure distribution: Sound pressure distributionhelps understand the sound interference between class-rooms and the declining level of sounds in classroomsof various layout types. The test method is:(a) Sound source: Sound source issues a pink audition
wave of 100 dB continuously as the sound sourcelevel. The speakers are placed at the center of theplatform.

(b) Sound reception: It is evenly distributed inside theclassroom. The test height is around 1.2–1.5m. Themicrophones are placed upwards keeping in mindthat locations close to walls, windows, doors, andaperture shall not be the test locations.

(c) Test method: The sound analyzer directly displaysthe noise level of 1/1 octave frequency at each

r

Measurement status Method

During the class hour, during the recess break, and

ambient background noise of the unoccupied

classrooms

ISO

1996

After class, adjusting division plates CNS

8463-

A3141

After class, original division plate layout ISO

3382

(1997)

ARTICLE IN PRESSC.-M. Chiang, C.-M. Lai / Building and Environment 43 (2008) 1619–16321626

location. Owing to the large area, test locationshave to be evenly distributed in the classrooms andmulti-learning space. Each classroom requires noless than four measuring points.

With steady state measurement, sound pressuredistributions of each classroom are made andinfluences of structure, materials, and room shapeon the distributions were discussed.

(3)
Reverberation time: RT is measured by impulse methodin accordance with ISO 3382 Measurement of theReverberation Time of Rooms with Reference toOther Acoustical Parameters. Test apparatus andmethod are:(a) Sound source: Issuing sound source with signal gun.(b) Sound reception: Non-directional microphone and
the affiliate pre-amplifier with sound analyzer.(c) Test method: Signal issuing impulse sound source.

Sound reception is 1.2m from ground and 1m fromwall.

4. Results and discussion

4.1. Analysis of questionnaires

Less time is spent in Joint Classrooms than traditionalclassrooms and most of the teachers using traditionalclassrooms have not used Joint Classrooms. Individualquestionnaires with teachers using Joint Classrooms andtraditional classrooms were both conducted. The ques-tionnaires included the background of teachers, overallscoring of teachers on the interior classroom environment,satisfaction, and comfort. As students in the classrooms

21-30 31-40

0%

20%

40%

60%

80%

100%

Straight Row JC Round curve JC S

Perc

enta

ge (

%)

Fig. 5. Age distributio

0%

20%

40%

60%

80%

100%

Straight Row JC Round curve JC S

Perc

enta

ge (

%)

0-5 6-10 11-15

Fig. 6. Tenure distribut

were in lower grades and had not used Joint Classroomsbefore, the questionnaires focused on the teachers this time.A total of 46 questionnaires for the 15 test spaces wereissued and 38 questionnaires were returned, with 34 valid.The ratio is 73.91%.

(1)

quare

n of

quar

16

ion

Characteristics of respondents: Schools in this study hada history of around 6 years and teachers were newlyhired. The ages and tenure of these teachers were lessthan those using the traditional classrooms (Figs. 5and 6). The teachers using Joint Classrooms werearound 30 years old. Teachers in curved Joint Class-rooms were the youngest—between 21 and 30. Theteaching tenure was between 1 and 5 years. Teachersusing traditional classrooms were older with a widerrange of tenure. Their ages were between 41 and 50 andtenure was between 26 and 30 years.

(2)
Space comfort and satisfaction: As shown in Figs. 7and 8, teachers in curved Joint Classrooms had thehighest score on space satisfaction and comfort.Teachers using L-shaped Joint Classrooms were lesssatisfied with the classroom space and did not find thespace comfortable. Teachers using square Joint Class-rooms were not totally satisfied with the space andabout half of them rated space comfort as ‘‘so-so’’,while the other half rated it ‘‘comfortable’’. Around60% of the teachers using straight row Joint Class-rooms believed them to be slightly inferior to quitepoor in space satisfaction. Traditional classrooms’space comfort and satisfaction appear to make teacherssatisfied and comfortable.
(3)
Acceptance of those using various types of Joint Class-
rooms and traditional classrooms: In respondents

41-50 51-60

JC L-shape JC Traditional

respondents.

e JC L-shape JC Traditional

-20 21-25 26-30 31

of respondents.

ARTICLE IN PRESS

0%

20%

40%

60%

80%

100%

Straight Row JC Round curve JC Square JC L-shape JC Traditional

Perc

enta

ge (

%)

worst bad fair good best

Fig. 7. Space satisfactions of teachers.

0%10%20%30%40%50%60%70%80%90%

100%


Perc

enta

ge (

%)


Fig. 8. Space comfort distribution of teachers.

0%

20%

40%

60%

80%

100%

Straight Row JC Roundcurve JC Square JC L-shape JC

Perc

enta

ge (

%)


Fig. 9. Acceptance comparisons of classroom users of both traditional classrooms’ and Joint Classrooms’ space.


(Fig. 9) using various types of Joint Classrooms, usersof most curved Joint Classrooms believed that JointClassrooms have better space than traditional class-rooms, while 75% of L-shaped Joint Classrooms usersbelieved the opposite.

(4)
Satisfaction ratings of interior acoustical environment by
respondents using various types of classrooms: As shownin Fig. 10, when rating the acoustic environment, of therespondents using the four types of Joint Classrooms,teachers using straight row Joint Classrooms had thelowest satisfaction. Around 85.71% of them feeldissatisfied or very dissatisfied. Fifty percent of theteachers using L-shaped Joint Classrooms felt verydissatisfied. In contrast, teachers using curved JointClassrooms had the highest satisfaction. Around 50%of respondents felt satisfied. Around 50% of theteachers using traditional classrooms felt dissatisfiedor very dissatisfied.

4.2. Analysis of on-site measurement results

(1)
LeqIn Fig. 11, the average noise levels during the class
hours and those during the recess breaks were comparedfor the 11 tests. During the class hour, when indoor noiseis measured, measurement of ambient background noiseof adjacent empty classrooms is also conducted. Theaverage indoor noise level spaces during a school day(windows opened) was 75.96dB (A) and that during theclass hour was between 70 and 78dB (A). The valueduring the recess break was between 74 and 83dB (A).During the recess break, students talk or play in theclassrooms or outside the classrooms (squares, play-grounds sports grounds, etc.), thus, the indoor noiseduring this time period is higher than that during classhours. All the values were significantly higher than thesuggested 55dB (A) (windows opened). Due to operation

ARTICLE IN PRESS

0%10%20%30%40%50%60%70%80%90%

100%


Perc

enta

ge (

%)


Fig. 10. Acoustic environment satisfaction distribution of users of various classrooms.

50

60

70

80

90

R-602 R-211 C-103 C-111 S-101 S-103 S-104 S-201 S-202 L-105 L-108

dB (

A)

during the class hour during the recess break daily average ambient backgrou ndnoise

StraightRow JC

Roundcurve JC

Square JCL-shape

JC

Suggeste dcriteria

Fig. 11. Comparisons of average indoor noise levels in the Joint Classrooms.

0.6

0.8

1

1.2

1.4

1.6

1.8

2

R-602 R-211 C-103 S-101 L-108

RT

(se

c)

500Hz 2000HzSuggested criteria

School A School B School DStraightRow JC

Square JCL-shapeJC

School CRound

curve JC

Fig. 12. RT distribution of tested spaces in 500 and 2000Hz.


noise of ceiling fans in the classrooms and the instruction-based teaching approach with students reading or doingactivities, the ambient background noise of the 11 testspaces during the class hours was between 50.49 and56.65dB (A), also close to the suggested 55dB (A). Theaverage difference between indoor noise and ambientbackground noise was 22.63dB (A).

(2)
RTRT was measured with windows and doors closed
and using the original partition layout. Except forsquare classrooms, the tested classrooms had longerRT in the suggested 0.6 s (Fig. 12). A possible reasonfor this is larger spatial volume. Provided that the sur-face materials do not have sufficient sound absorption,


verbal clarity or RT interference will be caused inclassrooms.

(3)
Sound pressure distribution(a) Influences of single sound source on neighboring
Joint ClassroomsWith a 100 dB (A) pink audition wave as the

sound source (mimicking the teacher’s voice),sound pressure distributions in the five JointClassrooms (four types) were measured, as shownin Fig. 13. Doors and windows were closed. Of thefive Joint Classrooms, only the classroom of SchoolA with a distance of two to the fourth classroom inthe original partition layout (open partition) had aninterior sound pressure meeting the standard 55 dB

Fig. 13. Sound pressure

(A). All of the rest were beyond the standard. In theclosed partition, in the classroom with a distance ofone to the third classroom, straight row and curvedJoint Classrooms had appropriate sound pressure.Owing to the number of partition plates and thefixed layout, square-shaped and L-shaped JointClassrooms in School D could not be simulated asclosed partition.

Various styles of classrooms affect other class-rooms differently. Using the single sound source,straight row, and curved Joint Classrooms directlyaffected the neighboring classroom (Fig. 13,Schools A, B, and C). Square and directly affectedthe neighboring classroom (Fig. 13, School D on

distri
bution.

ARTICLE IN PRESS

Fig.

Join


the left). L-shaped classroom directly affected theclassroom on the diagonal corner (Fig. 13, SchoolD on the right).

From the single sound source simulation, onecan understand that one classroom in a JointClassroom, having only a teacher teaching, willhave the above interference. With students’ volumeand the same volume in other classes, the inter-ference will be more serious. The sound pressuredistribution simulation used only one teacherteaching, compared with the above Leq values,the average is 75 dB (A). Sound interference inclassrooms is related to the space sound insulationmaterials and sound absorption. Classroom airtightness has to be increased for better soundinsulation. This is in conflict with the currentrequirement of openness.

(b) Use of partition platesBased on the current situations of the surveyed

classrooms, the acoustic environment of JointClassrooms is connected to the openness of thespace. Using more partition plates will reduce themutual interference among classrooms. Comparedwith traditional classrooms, Joint Classrooms havehigher flexibility to meet the purposes of differentcourses. It was found that partition plates at thesurveyed classrooms were not easily removed(Fig. 14). Some partition plates had rusted tracks

14.

t Cla

MPS

PartitionPlates

PartitionPlates

MPS

Partition plates of Joint Classrooms: (a) partition plates in the straight ro

ssroom at school C.

and some were unable to be moved owing to thebarrier of furniture, miscellaneous items, shelves,etc. Some required tools to be removed. Insufficienttools and use with other classes will reduce the ideaof space flexibility.

Joint Classrooms offer more diverse teachingspace and learning possibilities, offering functionsthat the traditional classrooms do not have.Maintaining the interactive and multi-purposelearning functions of Joint Classrooms and, whenquiet is required, having partition plates to add theindependence of space for flexibility, will effectivelyreduce the problem of noise.

(c) Fostering the habitsIn addition to partition plates and improving

sound absorption that helps improve verbal clarityand reduce echo interference, the most directimprovement is reducing the sound sources in theclassrooms. The best way is to persuade teachers, aswell as students, to practice good habits to reducethe noise interference. This requires education andtime to change. A private church school in Taiwanis a good example. Teachers set a good example andstudents become very quiet. However, leavingclassrooms, children return to their nature to runand shout. Thanks to soft voices of teachers and

MP

w Jo

students, the noise interference in classrooms isreduced significantly.

PartitionPlates

MPS

Classroom

S

PartitionPlates

int Classroom at school A and (b) partition plates in the square


4.3. Comprehensive evaluation of Joint Classrooms’ acoustic

environment

From Fig. 15, one learns that physical scorings of the 11tested Joint Classrooms were low. That of the four layoutstyles was between 20 and 30 and the physical amount failedto meet the standard of 60. Most of the mental scoring failedwith rates between 40 and 70. Most of the tested units werein the Area of Physical and Mental Scoring Discussion.

On the right of Fig. 15, 26.09% of the respondents feelthat the teaching space is slightly noisy; 21.74% think it isvery noisy; 43.48% think the noise is moderate; and 8.70%felt it was quiet. The converted mental scoring was 50.91.On the influence of noises in the classroom, 47.83% ofrespondents think they were highly affected; 8.70% feltthey were affected; and 43.48% felt the effect wasmoderate. The Leq average of the Joint Classrooms was97 dB (A) or converted into a physical scoring of 20. Themental scoring was higher than the physical one. The noisein the tested Joint Classrooms was indeed high.

The noise levels of the Joint Classrooms and traditionalclassrooms in this research exceeded 55dB (A) and Leq valuesexceeded 20dB (A) as per foreign standard. The interferencedifference of the two may not be the noise amount but that ofthe noise source. The noise source in the Joint Classrooms wasmainly caused by the teachers and students in adjoiningclasses. The noise source in the traditional classrooms was alsofrom neighboring classrooms, although not as serious. On thecontrary, what caused more serious interference was trafficnoise and sounds from nearby courts.

With T30 inspection, the researcher obtained the RTvalues. From Fig. 16 we find that except for square JointClassrooms, other Joint Classrooms have long RT, whichmay cause unclear verbal clarity and echo. Curved JointClassrooms had the longest RT. Based on 500Hz, theoverall average RT was 1.27 s or converted into a physical

0

10

20

30

40

50

60

70

80

90

100

0 10 20 30 40 50 60 70 80 90 100

Mental evaluation

Phys

ical

eva

luat

ion

Straight Row JC Round curve JC Square JC

L-shape JC traditional

BEST

BETTER

Area for Physical andMental Discussions

Area for PhysicalAspect Discussion

Area for MentalAspect Discussion

Bro

Fig. 15. Acoustic environment comparisons be

scoring of 32.73. In mental scoring, 4.35% of therespondents thought that the classrooms had very significantecho issues; 34.78% thought there was a slight echo issue;34.78% felt the issue was moderate; 17.39% felt there wasno echo and 8.70% felt there was no echo at all. The averagemental scoring was 58.26. Mental scoring is also higher thanphysical scoring in the echo issue. Nevertheless, both arerated in a failure area. In conclusion, most Joint Classroomsneed improvement in their overall acoustic environment.

5. Conclusion and suggestion

The space in classrooms is mainly for education. Themission of the designer is to design the space that meets therequirements of the users. For Joint Classrooms, the goal isto provide a comfortable and convenient space withoutaffecting the original function and open education method.Room noise values in both joint and traditional classroomswith open windows exceed the standard 20 dB (A). Owingto the larger volume of Joint Classrooms and insufficientsound absorption of the surface materials, the RT is longer,based on the suggested 0.6 s, with windows closed and inthe original partition layout. The difference in the acousticenvironment between joint and traditional classrooms isshown in Table 6.Joint Classrooms make people more aware of serious

sound interference, which might be the result of open spaceand more diverse noise sources. In other words, open spacewill lead to noise interference from nearby classrooms. Thebest way to reduce noise interference in open space is toreduce the noise volume and add sound insulation. This studysuggests the following to improve acoustic environment:

(1)

adca

twee

Reducing noise volume: The best way is to make teachersand students lower their volume when talking duringeducation and training, as it is the main sound source.

0

20

40

60

80

100Measured Leq

Verbal clarity

Measured RT

sting

Mental evaluation of JC

Physical evaluation of JC

Mental evaluation of the traditiona

Physical evaluation of the traditional

n physical scoring and mental scoring.

ARTICLE IN PRESS

Table 6

Comparisons of acoustic environment of Joint Classrooms and traditional

classrooms

Environment Traditional classrooms Joint Classrooms

Acoustical Leq value close to that of

Joint Classrooms.

Leq value close to that of

traditional classrooms.

Noise sources: mostly traffic

noise (engineering vehicles

and public vehicles), reading,

bustling, microphone of

teachers in nearby

classrooms.

Noise sources: reading from

other classrooms,

microphone of teachers in

nearby classrooms and

children playing in the MPS.

Better RT. Poor RT.

0.00.20.40.60.81.01.21.41.61.82.0

63 125 250 500 1000 2000 4000

Frequency (Hz)

RT

(se

c)

Straight Row JCs at school A Straight Row JCs at school B Round curve JCs at school C

L-shape JCs at school C Square JCs at school D L-shape JCs at school DThe traditional at school E The traditional at school F-1 The traditional at school F-2

Fig. 16. Comparisons of RT in each tested spaces.


(2)
Improving surface material sound absorption: LongerRT in Joint Classrooms may cause insufficient verbalclarity or echo issues. Proper renovation, such asadding curtains and sound absorbers, etc., increasessound absorption of surface materials and increaseseducation quality.
(3)
Using safe, movable, durable, and good sound absorption
partition plates: Use of partition plates will help reducethe mutual interference among Joint Classrooms. Theseshould have higher flexibility for use in various courses.The flexibility of the partition plates becomes moreimportant when sound interference is brought aboutbecause of open classrooms. Joint Classrooms arehaving problems with their partition plates as men-tioned above. Therefore, durable, safe, and good soundabsorption partition plates are recommended in thefuture design.

Acknowledgment

My sincere gratitude goes to Miss Zhen-Yan Huang,Master of Architecture at National Cheng-Kung University,Taiwan, for her assistance throughout the measurements.

References

[1] Huang SM. Issues of School Buildings Program in open education

environment. Architecture Journal 1996;19:85–100.

[2] Lin TT. Pose-occupation evaluation of Joint Classrooms at

elementary schools. Master thesis paper, Graduate Institute of Civil

Engineering, National Taiwan University; 2000.

[3] Gao JZ. Study on usage and space conversion of regular classrooms

at elementary schools. Master thesis paper, National Cheng Kung

University; 1992.

[4] Environmental Protection Agency. Noise vibration control policies

and execution evaluation. Books on environment protection policies

analysis; 1988.

[5] Mills JH. Noise and children: a review of literature. Journal of the

Acoustical Society of America 1975;58(4):767–91.

[6] Xue FJ. Flexible programs and evaluation study on Elementary

School Joint Classrooms. Ph.D. thesis paper, Graduate Institute of

Civil Engineering, National Taiwan University; 2002.

[7] Zhang CY. Post-occupation evaluation on Joint Classrooms at

Elementary Schools in Kaohsiung City. Master thesis paper,

Graduate Institute of Education, National Kaohsiung Normal

University; 2004.

[8] Huang ZY. The study of the physical indoor environment for

primary school classrooms in Kaohsiung, Taiwan. Master thesis

paper, Graduate Institute of Architecture, National Cheng Kung

University; 2005.

[9] WHO, 1997. Primary school physical environment and health, WHO

information series on school health: Document 2.

[10] California Air Resources Board. Environmental health conditions in

California’s portable classrooms. California Department of Health

Services; 2004.

Documents

Acoustic Evaluation Method Taiwan