International Workshop on Frontiers in Speech and Hearing Research, Technical Report of IEICE Japan, Vol. SP2005-172, pp. 55-60, 2006
Speech processing for hearing-impaired listeners considering threshold elevation in the critical band with an expanded auditory filter
S. Minamihata, K. Yasu, K. Kobayashi, T. Arai and M. Shindo
Abstract: Elevation of the threshold of audibility occurs in hearing-impaired people, and these individuals have an expanded auditory filter (Glasberg and Moore, 1986). Threshold elevation is assumed to occur due to an increase in frequency components that pass the auditory filter; an assumption known as the “power spectrum model” of masking (Patterson and Moore, 1986). Therefore, we attempted here to remove from the speech signal the frequency components that are not related to speech perception, but are instead related to threshold elevation. We calculated the masking pattern using the spreading function (Painter and Spanias, 1997), and processed monosyllabic speech samples using nine kinds of masking patterns. Both normal-hearing and hearing-impaired subjects evaluated the intelligibility and sound quality of the original and processed monosyllables. For hearing-impaired subjects, the intelligibility of a small number of certain processed monosyllables increased, but sound quality did not improve. For normal-hearing subjects, speech intelligibility decreased as the masking pattern expanded, and application of the proposed method showed no significant improvement in sound quality.
Keywords: Auditory Filter, Threshold of Audibility, Critical Band, Spreading Function