Multichannel compression hearing aids: effect of number of channels on speech discrimination in noise.

Full-range multichannel compression hearing aids (MCCHAs) with 4, 6, 8, 12, and 16 independent frequency channels were used to determine the effect of the number of channels on the speech discrimination of mild to moderately severe hearing-impaired subjects. Signal-to-noise ratios (S/Ns) from -5 to 15 dB with speech-spectrum noise (70 dB SPL) and two voices (male and female) were used. Average speech discrimination for 16 hearing-impaired subjects increased from 4 to 8 channels but did not change significantly between 8 and 16 channels. The effect of the number of channels did not vary significantly with S/N. Analyses of speech discrimination performance within phonemic categories as well as consonant-confusion analyses revealed response shifts with the number of channels that were consistent with increasing transmission of useful high-frequency speech information as the number of channels increased. These results indicate that a MCCHA with at least 8 (and up to 16) channels provides the mild to moderately severe hearing-impaired subjects with acoustic information that facilitates speech discrimination in speech-band noise.