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creating sound valueTM
The perceptibility, acceptability, and benefit of transitioning to new gain targets in experienced hearing aid wearers with moderately severe to
profound hearing loss
Elizabeth Convery and Gitte KeidserNational Acoustic Laboratories and the HEARing CRC
Audiology Australia’s XIX National Conference, May 2010, Sydney
www.hearingcrc.org creating sound valueTM
creating sound valueTM
Introduction
severe and profound
hearing loss
long-term hearing aid users
reluctant to alter amplification
characteristics
retain older technology for
longer
adapt to frequency response with +LF and –HF gain
↓ speech understanding due to upward spread of masking
full-timehearing aid users
highly reliant on amplification
}
creating sound valueTM
Introduction
• technology currently available to meet HF gain requirements of people with severe and profound hearing loss– increased bandwidth– more sophisticated feedback cancellers
• best way to introduce new amplification characteristics?– gradual introduction shown to be successful
for introducing multichannel WDRC (Kuk 2001, Kuk et al. 2003, Keidser et al. 2007)
creating sound valueTM
• to investigate the effect of a gradual change in gain/frequency response on experienced hearing aid users with moderately severe to profound loss
Objective
– do they accept the
– do they benefit
– is the transition
change?
objectively, subjectively?
perceptually disturbing?
creating sound valueTM
• 23 experienced hearing aid users• PTA ≥ 60 dB HL
• devices set to match gain/frequency response of participants’ own devices for a 65 dB SPL input
Method
• wore the Siemens Artis 2
SP for 15 weeks
“mimic fit”
creating sound valueTM
100 1000 100000
5
10
15
20
25
30
35
40
45
50
Mimic fit
NAL-RP
Frequency (Hz)
2 cc
Co
up
ler
Gai
n (
dB
)Results – mimic fit vs NAL-RP
overfit in mid frequencies re: NAL-RP
underfit in high frequenciesre: NAL-RP
creating sound valueTM
Method
Expgroup
Controlgroup
age = 68 yrsPTA = 79 dB HL
50%25% NAL-RP75%
Week 15Week 12Week 9Week 6Week 3
mimic fit
mimic fitage = 64 yrs
PTA = 79 dB HL
Week 1
PC SDLSQ
SDLSQ
SDLSQ
SDLSQ
SDLSQ
Subjective tests: paired comparison, questionnaireObjective tests: speech discrimination, loudness scaling
PC
creating sound valueTM
• no significant change in any of these factors over time, or between groups:– perception of loudness, sound quality, speech
intelligibility, own voice volume– overall performance rating– presence and degree of perceptual
disturbance
Results – subjective feedback
experimental participants were accepting of the gradual change to their amplification characteristics, and did not experience greater perceptual disturbance than control participants
creating sound valueTM
• speech discrimination
Results – objective tests
performance of control participants improved over time - acclimatisation or learning effect
experimental group participants had greater difficulty as settings reached the NAL-RP prescription
Interaction between group and timep = 0.0005
creating sound valueTM
• loudness scaling
Results – objective tests
experimental group tended to find mid-level sounds softer over time than did control participants
Interaction between group and timep = 0.44
creating sound valueTM
• mimic fit program preferred to NAL-RP overall
Results – paired comparison
suggest that experimental participants did undergo some adaptation to the new settings during the 15-week study period
control groupmaintained or slightly increased their preference for mimic fit between weeks 1 and 15
experimental groupshowed a lesser preference for mimic fit at week 15 than at week 1
p = 0.09
creating sound valueTM
• evidence in support of gain transitionnot perceptually disturbing to participants
participants not aware of changes to loudness, speech understanding, sound quality
less preference for original settings after 15 weeks
• evidence that does not support transitiondecline in speech discrimination performance
Conclusions
individual variation longer increment intervals?
creating sound valueTM
• Gain transition... – only initiate transition if there is a compelling
reason• risk of TTS/PTS due to overamplification• poorer than expected speech discrimination re:
pure tone thresholds• complaints about sound quality
– ensure an appropriate transition goal– monitor speech discrimination over time
• be prepared to stop, or delay, transition if performance decrements are observed
Clinical recommendations
or no?yesyes, BUT
creating sound valueTM
Acknowledgements
creating sound valueTM
This research was financially supported by the HEARing CRC established and supported under the Australian Government’s Cooperative Research Centres Program
from the National Acoustic Laboratories
Anna O’Brien, Margot McLelland, Ingrid Yeend, Megan Gilliver, Vivian Fabricatorian, Pamela Jackson, Emma van Wanrooy, Elizabeth Beach
from Siemens Audiologische Technik
Simone Siltmann, Dirk Junius