The relative importance of consonant and vowel segments to the recognition of words and sentences: effects of age and hearing loss.

This study investigated the ability to use cues contained within vowel and consonant segments by older listeners with normal or impaired hearing. Spectral shaping restored audibility for the hearing-impaired group. Word and sentence materials were processed to contain primarily consonants or vowels by replacing segments with low-level speech-shaped noise. The proportion of the total duration of preserved speech was varied by manipulating the amount of transitional information contained within vowel and consonant segments. Older listeners performed more poorly than young listeners on all conditions except when listening to sentences with only the vowels preserved. Results confirmed a greater contribution to intelligibility of vowel segments in sentences, but not in words, for young normal-hearing, older normal-hearing, and older hearing-impaired listeners. Older listeners received a greater benefit than young listeners from vowels presented in a sentence context. Correlation analyses among the older listeners demonstrated an association between consonant and vowel performance in isolated words but not in sentences. In addition, the use of vowel cues in sentences was relatively independent of age and auditory sensitivity when audibility is ensured. Combined, results argue that older listeners are able to use essential cues carried by vowels for sentence intelligibility.