Characterization of non-linear distortion in hearing aids using coherence analysis. A pilot study.
Coherence is a frequency-domain measure of linear dependence between input and output of a system, e.g. a hearing aid, and describes the cumulative effect of different forms of signal corruption, e.g. noise and non-linear distortion. From the coherence function, a general frequency-dependent signal-to-noise ratio can be derived. In this investigation, the applicability of this measuring technique is demonstrated in connection with non-linear distortion in hearing aids. The influence of hearing aid gain and automatic gain control is illustrated, with speech-shaped noise as input signal. For the three hearing aids tested. The gain setting influences the signal-to-noise ratio heavily due to non-linear distortion, especially near maximum gain. The introduction of automatic gain control reduces the effect of non-linear distortion somewhat at high gain settings.
Dyrlund
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Technical-Audiological Department, School for Deaf and Profoundly Hard-of-Hearing Children, Fredericia, Denmark.
D006310:Hearing Aids; D010865:Pilot Projects; D013016:Sound; D013269:Stochastic Processes