Laryngeal kinematics in voiceless obstruents produced by hearing-impaired speakers.

During normal production of voiceless consonants several events occur simultaneously in the vocal tract. These events must be temporally coordinated. Earlier work has indicated that a breakdown in interarticulator timing can contribute to the characteristic voiced-voiceless errors produced by hearing-impaired speakers. The present study examines kinematic details of the laryngeal articulatory gesture in 2 deaf speakers and a control subject using transillumination of the larynx. Results indicate that hearing-impaired speakers often do not produce differences between stops and fricatives in the kinematic details of the gesture. That is to say, although hearing speakers commonly use a larger laryngeal gesture for fricatives than for stops and also show durational differences of the abduction and the adduction phases between phonetic categories, the hearing-impaired subjects did not make them. Also, the deaf speakers participating in this study were more variable in the kinematic measures.