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.