The effect of varying the amplitude-frequency response on the masked SRT for sentences in hearing-impaired listeners

Abstract

A multichannel gain-control hearing aid, in which the frequency-dependent amplification is adapted automatically to the fluctuations of the incoming signal,. may optimally deliver speech to an impaired ear. Such a system requires that the speech-reception threshold (SRT) in noise is, within limits, unaffected by dynamic variations in the amplitude-frequency response of the hearing aid. For normal-hearing listeners, van Dijkhuizen et al. [J. Acoust. Soc. Am. 81, 465–496 (1987)] found that the masked SRT for sentences is remarkably resistant to dynamic variations in the slope of the amplitude-frequency response when it shaped both speech and noise. In this experiment, we studied corresponding conditions for hearing-impaired listeners. Again, the amplitude-frequency response shaped both speech and noise and thus left speech-to-noise ratios untouched. The results obtained so far also indicate that, for hearing-impaired listeners, dynamic variations of the amplitude-frequency response do not affect the SRT.