Vowel errors in noise and in reverberation by hearing-impaired listeners.

The effects of noise and reverberation on identification of monothongs and diphthongs were evaluated using ten subjects with moderate sensorineural hearing losses. Stimuli were 15 English vowels, spoken between /b/ and /t/ and recorded in a carrier sentence. The test was recorded without reverberation under quiet conditions then degraded either by recording in a room with reverberation time 1.2 s or by adding babble of 12 voices at speech-to-noise ratio of 0 dB. Both degradations caused statistically significant reductions of mean identification scores, but the difference between degraded means was not significant. The pattern of errors was different in noise and reverberation. Errors for monothongs in reverberation seemed to be related to an overestimation of vowel duration and to a tendency to perceive the pitch of the formant frequencies as being higher than without reverberation. Errors for monothongs in noise were not related to duration or pitch overestimation. Errors involving diphthongs were more frequent in reverberation than in noise. In reverberation, there was a tendency to judge a diphthong as the beginning monothong. [ABSTRACT FROM AUTHOR]