Multichannel compression hearing aids: experiments and consideration on clinical applicability

The rational for applying multichannel compression in connection with peripheral perceptive hearing loss is briefly discussed. The speech transfer ability of a multichannel compression hearing aid with up to 4 channels is evaluated on high tone hearing impaired subjects. The compression characteristic of each channel is individually fitted to compensate on average the loudness recruitment of the subject's hearing within each individually determined frequency band. Experiments on 5 subjects under several signal-to-noise ratio conditions reveal that 4-channel recruitment compensation is indistinguishable in performance from an "optimally" fitted linear hearing aid which takes advantage of the limited dynamic range of the applied speech signal. Contrarily, 3- and 2-channel configurations investigated show in general degraded performance on speech compared to this condition. The results obtained and their implications for the design objectives of future multichannel compression hearing aids and the clinical fitting of such an aid are discussed.