The effect of varying the amplitude-frequency response on the masked speech-reception threshold for sentences in conditions with low-frequency noise

Abstract

Within a study on the merits of a frequency-dependent automatic gain control in hearing aids, the beneficial effect of adapting the amplitude-frequency response to situations of seriously interfering low-frequency noise is studied. For 12 normal-hearing and 12 hearing-impaired listeners, the masked speech-reception threshold (SRT) for sentences is measured. The noise has a spectrum identical to the long-term average spectrum of the sentences, but with its level in one octave band raised by a constant 20 dB in the first experiment, and slowly increasing by 20 dB during sentence presentation in the second experiment. Results indicate that, in conditions with steady-state noise, selective attenuation of the signal in the band containing the extra noise gives an improvement of speech intelligibility in terms of speech-to-noise ratio of up to about 4 dB for both the normal-hearing and hearing-impaired group. In conditions with time-varying noise, a similar improvement was observed for both groups.