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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

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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

}

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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)

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• 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?

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• 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”

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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

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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

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• 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

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• 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

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• 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

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• 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

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• 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?

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• 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

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Acknowledgements

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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