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Prevalence of Cochlear Dead Regions in New Referrals and Existing Adult Hearing Aid Users

Pepler, Anna1; Munro, Kevin J.1,2; Lewis, Kathryn3; Kluk, Karolina1

doi: 10.1097/AUD.0000000000000011
e-Research Articles

Objectives: The primary aim of this study was to identify the prevalence of dead regions (DRs) in new adult hearing aid referrals and existing adult hearing aid users. Secondary aims included determining the effect of hearing threshold levels and slope, age, and sex on the presence of DRs.

Design: Three hundred and seventy-six adults were recruited from a U.K. National Health Service audiology clinic. Three hundred and forty-three participants (674 ears) with a sensorineural hearing impairment were assessed for the presence of a DR at audiometric frequencies from 0.5 to 4 kHz using the Threshold Equalizing Noise test.

Results: The overall prevalence of DRs was 36% (95% confidence interval 31–41). The prevalence in new referrals, and in new and existing hearing aid users was 31% (25–37), 33% (26–40), and 43% (35–51), respectively. The overall prevalence of extensive DRs, defined as spanning ≥3 consecutive frequencies, was 3% (1–5).

Conclusions: On the basis of the findings from the Threshold Equalizing Noise test, prevalence of DRs was relatively high in adult hearing aid users with a sensorineural hearing impairment. However, in most cases, the DR was limited to a small frequency region. This suggests that, in most cases, the presence of a DR may not be clinically significant. The difference in DR prevalence between new referrals and existing hearing aid users was not statistically significant. Hearing threshold levels, slope of hearing impairment, age, and sex could not be used to reliably identify DRs.

Little is known about the prevalence of cochlear dead regions (DRs) in new referrals and existing adult hearing aid users. Using the Threshold Equalizing Noise test, we estimated the prevalence of DRs in new referrals and existing hearing aid users who attended a U.K. audiology department, funded by the National Health Service. More than one in three participants met the criteria for a DR (prevalence of 36%; 95% confidence interval: 31–41). In half of the cases, this was at a single audiometric test frequency. There was no significant difference in DR prevalence between new referrals and existing hearing aid users.

1School of Psychological Sciences, University of Manchester, Manchester, United Kingdom; and 2Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, United Kingdom; and 3Audiology Department, University Hospitals South Manchester NHS Foundation Trust, Manchester, United Kingdom.

The views expressed are those of the author(s) and not necessarily those of the National Health Service, the NIHR or the Department of Health.

The authors declare no other conflict of interest.

Address for correspondence: Anna Pepler, School of Psychological Sciences, Ellen Wilkinson Building, University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom. E-mail:

© 2014 by Lippincott Williams & Wilkins