Preferred gain levels of new and experienced hearing aid users: is there really a difference

1
Preferred gain levels of new and experienced
hearing aid users is there really a difference?

• Elizabeth Convery, MS, Research Audiologist
• Gitte Keidser, PhD, Senior Research Scientist
• Harvey Dillon, PhD, Research Director

2
Introduction

• there is a widespread belief among audiologists
  in clinical practice that new users of hearing
  aids prefer lower gain levels than do experienced
  hearing aid users
• this view has been reinforced by
• proprietary fitting software, which often
  incorporates lower gain targets or
  acclimatisation levels for hearing aid users
  with no prior amplification experience
• studies of benefit based on unsupported
  assumptions that new hearing aid users will come
  to prefer higher gain settings over time as they
  acclimatise to amplification (Gatehouse 1992)

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Does this belief have validity?

• a review of the existing literature was conducted
  to answer the following questions
• is there a significant difference between the
  gain preferences of new and experienced hearing
  aid users?
• do the gain preferences of new users change over
  the first 12 months of hearing aid use?

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Reviewed publications

• 11 studies covering 27 years of research

• Walden et al (1977)
• Berger and Hagberg (1982)
• Byrne and Cotton (1988)
• Leijon et al (1990)
• Mueller et al (1991)
• Cox and Alexander (1992)

• Bentler et al (1993)
• Horwitz and Turner (1997)
• Arlinger et al (2000)
• Humes et al (2002)
• Marriage, Moore, and Alcántara (2004)

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Literature overview

• aims of the research varied across studies and
  were not always directly related to the issue of
  gain preferences, for example
• to examine hearing aid usage patterns in new
  users with normal thresholds below 3 kHz (Mueller
  et al 1991)
• to investigate the effectiveness of currently
  available objective and subjective hearing aid
  benefit measures (Bentler et al 1993)
• number of subjects ranged from 12 to 344 (median
  25)
• use gain levels were measured in response to a
  variety of stimuli in both real-life listening
  situations and controlled laboratory conditions

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But...

• few studies have directly addressed the issue of
  new and experienced hearing aid users gain
  preferences
• data from four studies were obtained and examined
  in closer detail
• Byrne and Cotton (1988)
• Cox and Alexander (1992)
• Horwitz and Turner (1997)
• Humes et al (2002)

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Audiometric data 3FA

• average hearing losses of the experienced groups
  are greater than those of the new groups

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Audiometric data slope

• average slopes of the new groups are steeper than
  those of the experienced groups

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Use gain comparison

• the actual preferred use gain of new and
  experienced hearing aid users could not be
  directly compared due to the greater average
  hearing losses and flatter audiometric
  configurations of the experienced subjects
• therefore, the reported use gain was subtracted
  from the NAL-RP 2cc coupler targets to eliminate
  the effect of varying degrees of hearing loss

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Question 1

• is there a significant difference between the
  gain preferences of new and experienced hearing
  aid users?

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Use gain new vs. experienced

• Byrne and Cotton (1988)

one-way ANOVA relationship between prescribed
and used gain not significantly affected by
experience (p gt 0.20)
12
Use gain new vs. experienced

• Cox and Alexander (1992)

t-test no significant effect of experience on
preferred gain in each acoustic environment p
values ranged from 0.54 to 0.95

• Environment A face-to-face in quiet, full visual
  cues (S55 dBA/N48 dBA)
• Environment B low noise/high reverberation, no
  visual cues (S63 dBA/N55 dBA)
• Environment C face-to-face in high noise, full
  visual cues (S64 dBA/N62 dBA)
• Environment D face-to-face in high noise, no
  visual cues (S64 dBA/N62 dBA)

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Use gain new vs. experienced

• Horwitz and Turner (1997)

t-test no significant effect of experience on
preferred gain at each post-fit interval p
values ranged from 0.43 to 0.96
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Use gain new vs. experienced

• Humes et al (2002)

Mann-Whitney U test conducted because individual
data points not available showed no significant
difference between gain preferences of new and
experienced users (p gt 0.05)
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Conclusion Question 1

• is there a significant difference between the
  gain preferences of new and experienced hearing
  aid users?
• no experienced hearing aid users do not, on
  average, prefer more gain than do new hearing aid
  users
• the average difference in preferred gain reported
  by the four studies was never greater than 2 dB

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Question 2

• do the gain preferences of new users change over
  the first 12 months of hearing aid use?

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Use gain change over time

• Horwitz and Turner (1997)

repeated measures ANOVA no significant effect of
post-fit interval (p 0.68) was found no
significant interaction between experience and
post-fit interval (p 0.76)
18
Use gain change over time

• Humes et al (2002)

repeated measures ANOVA no significant effect of
post-fit interval was observed (p gt 0.01)
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Conclusion Question 2

• do the gain preferences of new users change over
  the first 12 months of hearing aid use?
• no the preferred use gain of new hearing aid
  users neither increases nor decreases during the
  first year of amplification experience
• but more research, directly addressing these
  questions, is needed

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Suggestions for further research

• audiometric characteristics (3FA and slope) of
  new and experienced hearing aid users should be
  matched
• standard definition of what constitutes an
  experienced hearing aid user should be
  established
• studies greater than one year in duration may be
  warranted to determine whether acclimatisation
  effects are present over the longer term

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Suggestions for further research

• the circuitry of the hearing aids used should not
  limit the gain range available to the more
  severely hearing-impaired subjects
• when obtaining use gain measurements, the effects
  of the following are known to be significant and
  should be controlled
• test room environment (Cox and Alexander 1991)
• frequency response of stimulus (Kuk and Lau 1996)
• intensity level of stimulus (Cox and Alexander
  1992)

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References

• Arlinger S et al (2000) Fitting hearing aids to
  first-time users. Scandinavian Audiology 29
  150-158.
• Bentler RA et al (1993) Longitudinal study of
  hearing aid effectiveness. I Objective measures.
  Journal of Speech and Hearing Research 36
  808-819
• Berger KW and Hagberg EN (1982) Gain usage based
  on hearing aid experience and subject age. Ear
  and Hearing 3 (4) 235-237.
• Byrne D and Cotton S (1988) Evaluation of the
  National Acoustic Laboratories new hearing aid
  selection procedure. Journal of Speech and
  Hearing Research 31 178-186.

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References

• Cox RM and Alexander GC (1991) Preferred hearing
  aid gain in everyday environments. Ear and
  Hearing 12 (2) 123-126.
• Cox RM and Alexander GC (1992) Maturation of
  hearing aid benefit objective and subjective
  measurements. Ear and Hearing 13 (3) 131-141.
• Gatehouse S (1992) The time course and magnitude
  of perceptual acclimatization to frequency
  responses evidence from monaural fitting of
  hearing aids. Journal of the Acoustical Society
  of America 92 (3) 1258-1268.
• Horwitz AR and Turner CW (1997) The time course
  of hearing aid benefit. Ear and Hearing 18 (1)
  1-11.

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References

• Humes LE et al (2000) Prescribed clinician-fit
  versus as-worn coupler gain in a group of elderly
  hearing-aid wearers. Journal of Speech, Language,
  and Hearing Research 43 (4) 879-892.
• Humes LE et al (2002) Changes in hearing-aid
  benefit following 1 or 2 years of hearing-aid use
  by older adults. Journal of Speech, Language, and
  Hearing Research 45 (4) 772-782.
• Kuk FK and Lau C (1996) Effect of hearing aid
  experience on preferred insertion gain selection.
  Journal of the American Academy of Audiology 7
  274-281.
• Leijon A et al (1984) Preferred hearing aid gain
  and bass-cut in relation to prescriptive fitting.
  Scandinavian Audiology 13 157-161.

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References

• Leijon A et al (1990) Preferred hearing aid gain
  in everyday use after prescriptive fitting. Ear
  and Hearing 11 (4) 299-305.
• Mueller HG et al (1991) Hearing aid selection for
  high-frequency hearing loss. In G Studebaker, F
  Bess, and L Beck (eds), The Vanderbilt Hearing
  Aid Report II. Parkton, MD York Press.
• Walden BE et al (1977) The reliability and
  validity of the comfort level method of setting
  hearing aid gain. Journal of Speech and Hearing
  Disorders 42 (4) 455-461.