Co-channel speech separation for assistive listening

A study is made on applying adaptive decorrelation filtering (ADF) to the design of an assistive listening system. The speech signal of a desired talker was corrupted by three simultaneous speech jammers and a speech-shaped diffusive noise. ADF was used to extract the desired speech from the jammers and noise. The effectiveness of the assistive listening system was measured by improvement in signal-to-noise ratio (SNR) and in word correct percentage, with the latter evaluated by a formal clinical test on subjects of both normal and impaired hearings. Significant gains in SNR and word correct percentage were obtained with the use of the assistive listening system. On eight subjects with normal hearing, the speech reception threshold was improved by 3 to 5 dBA, and on three subjects with hearing impairments, the threshold was improved by 4 to 8 dBA.