An Acoustic and Electromyographic Investigation of Consonant-Vowel Transitions in the Speech of Deaf Adults

Abstract

An acoustic and electromyographic investigation of the speech of normal-hearing and deaf speakers attempted to answer questions concerning formant transitions, coarticulation, and neutralization of vowels in the speech of deaf adults. In order to accomplish this, EMG and acoustic recordings were made simultaneously as each subject read a constant phrase into which a variable key word was embedded. The deaf speakers chosen for this study were judged to be above average in intelligibility for deaf talkers with a profound bilateral hearing loss of early onset. Acoustical analysis was performed by making wide-band spectrograms of selected recorded stimulus items. The amplitude display of the sonograph was used for relating electromyographic events to acoustic events in time. The results of this study showed that the transitions of deaf speakers had a restricted range of movement and a slower rate of movement than those of normal speakers. The speech of the deaf shows relatively small coarticulation effects, their vowels tend to be neutralized regardless of the context, and they tend to begin an articulatory sequence in a similar manner regardless of the context. The deaf speakers also exhibited difficulty coordinating articulation with phonation and their articulatory behavior showed greater variability than did the articulatory behavior of the normal speakers. The discussion of the results will indicate their implications for speech training of the deaf.