Observations on hearing aid users' strategies for controlling the level of their own voice.

BACKGROUND Evidence suggests that hearing-aid users have difficulties with own-voice level control, most likely because their auditory feedback is affected by hearing-aid amplification. PURPOSE The purpose of this study was to investigate how changes to auditory feedback affect the voice level of hearing-aid users. RESEARCH DESIGN A correlational study was set up to investigate the relation between voice level and hearing-aid amplification. STUDY SAMPLE Seven hearing-impaired speakers participated. All were experienced hearing-aid users. DATA COLLECTION AND ANALYSIS The speakers projected their voice to a passive listener across different speaker-listener distances and with different prescriptions of gain in an experimental hearing aid. For each combination of conditions, produced voice level and self-perceived voice level was measured. These data were subjected to an analysis of variance assuming a mixture of random and fixed effects. In addition, all speakers took part in interviews. RESULTS Three speakers reacted to the changes in auditory feedback in agreement with previous experiments with normal-hearing speakers: they compensated by changing produced voice level. In contrast, the voice levels in the other four speakers were largely unaffected by the changes to auditory feedback. A secondary observation was that while all speakers increased their voice level with distance, the two subgroups produced different growth rates of vocal level versus distance. CONCLUSIONS It is hypothesized that the speakers in the former subgroup relied on auditory feedback for solving the experimental task, whereas the latter subgroup had developed an own-voice level-control strategy based on proprioceptory feedback, possibly because they have lost faith in their auditory feedback mechanism, which indeed is changed by both hearing loss and hearing-aid amplification. Comparison to "target" voice levels suggests that proprioceptory feedback is less effective than auditory feedback for achieving adequate level-distance growth rate.