The effect of a hearing aid on the speech-reception threshold of hearing-impaired listeners in quiet and in noise

Abstract

The monaural free-field speech-reception threshold (SRT) without and with a hearing aid was investigated for conversational sentences presented to 50 hearing-impaired [human] listeners. SRT without a hearing aid was measured in quiet and in noise at levels of 40, 55, 70 and 85 dBA. SRT with a hearing aid was obtained in quiet and at noise levels of 25, 40, 55 and 70 dBA. The noise had a long-term average spectrum equal to that of the sentences. The 50 subjects were equally distributed over 5.degree. of pure-tone hearing loss and 5 types of hearing impairment (sensorineural high-frequency losses, with or without recruitment; flat audiogram of a sensorineural, mixed, or conductive origin). A model of SRT as a function of noise level, developed by Plomp (1978) gives a good description of the SRT values measured, both without and with a hearing aid. Apparently, current hearing aids do not improve speech intelligibility in noise beyond, roughly, 60 dBA.