Contribution of consonant versus vowel information to sentence intelligibility by normal and hearing-impaired listeners

Abstract

The purpose of this study was to examine the contribution of information provided by vowels versus consonants to sentence intelligibility in young normal-hearing (YNH) and elderly hearing-impaired (EHI) listeners. Sentences were presented in three conditions, with either the vowels or the consonants replaced with speech shaped noise, or unaltered. Sentences from male and female talkers in the TIMIT database were selected. EHI subjects listened at 95 dB SPL, and YNH subjects at both 95 and 70 dB SPL. Subjects listened to each sentence twice and were asked to repeat the entire sentence after each presentation. Words were scored correct if identified exactly. Average performance for unaltered sentences was greater than 94%. Vowel-present conditions were always significantly more intelligible than consonant-present conditions, similar to data reported by Cole and colleagues [Proceedings of ICASSP, 1996]. Across groups, performance in the vowel-present conditions exceeded that in the consonant-present conditions by 14% to 40%, although EHI subjects performed more poorly than YNH subjects. In contrast to written English, vowels in spoken language carry more information about sentences than consonants for both normal and hearing-impaired listeners. [Work supported by NIDCD-02229.]