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.
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.
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).
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.