Effects of modifying the time‐varying amplitude patterns on perception of speech by hearing‐impaired and normal listeners

Abstract

The acoustical patterns of speech may be analyzed into three primary components: a fine‐temporal pattern, a gross‐temporal pattern, and a time‐varying amplitude pattern. Previous research has supported the importance of both fine‐ and gross‐temporal cues for speech perception. Braida et al. [ASHA Monographs 19 (1979)] reviewed amplitude compression, and indicated that the importance of time‐varying amplitude patterns was not well understood. The present research utilized altered versions of the California Consonant Test to examine perception by hearing impaired and normals. The time‐varying amplitude patterns had been systematically altered to simulate the effects of several types of single‐ and multichannel compressors. The effects of frequency response, degree of compression, and number of channels have been statistically analyzed using ANOVA. Results for the hearing impaired showed significant improvements in consonant differentiation for severe rather than mild compression ratios, and for compression preceded by high‐frequency emphasis. Multichannel designs did not perform better than optimal single‐channel designs. The time‐varying amplitude pattern seems of little importance for the speech intelligibility.