Multiband syllabic compression for severely impaired listeners

Abstract

Speech reception experiments were conducted to evaluate the benefit of multiband syllabic compression for listeners with severe sensorineural hearing impairments. Three listeners with congenital hearing loss characterized by flat audiograms and dynamic ranges of 20–30 dB were tested on three compression systems and one linear amplification system. The compression systems placed progressively larger amounts of speech energy within the listener's residual dynamic range by raising to audibility and compressing 25%, 50%, and 90% of the short‐term input amplitude distribution in each of 16 frequency bands. The comparison linear system was defined by adjusting six octave‐wide bands of speech to comfortable levels. System performance was evaluated with nonsense CVC syllables presented at a constant input level and spoken by two talkers. Extensive training was provided to ensure stable performance. The results were notably speaker dependent, with compression consistently providing better performance for one, linear amplification for the other. Averaged over speakers, however, there was no net advantage for any of the compression systems for any listener. The use of high compression ratios and large input ranges tended to degrade perception of initial consonants and vowels. Under some conditions, however, final consonant scores were higher with compression than with linear amplification. Detailed summaries of system performance and analyses of consonant and vowel confusions will be presented. [Work supported by NIH.]