A single-microphone-based self-adaptive filter of noise from speech and its performance evaluation

This paper discusses a single-microphone-based self-adaptive filter of environmental noise from speech. This filter, based on the work of Graupe (3) and of Graupe and Causey (4), has been incorporated in standard in-the-ear (ITE) and in behind-the-ear (BTE) hearing aids by several hearing aid manufacturers. Intelligibility tests by the authors and by independent researchers are presented in this paper to illustrate the filter's performance. Significant monosyllabic-word-list intelligibility improvements are shown in hearing-impaired and in normal-hearing subjects for virtually any environmental noise, including white noise, babble (interfering background conversations), cafeteria noise, high-frequency noise, and low-frequency noise at signal-to-noise ratios to below -20 dB.