Effects of vocal task and respiratory phase on prephonatory chest wall movements.

A vocal reaction time paradigm was used to explore prephonatory respiratory kinematics. Movements of the rib cage and abdomen were recorded prior to production of utterances differing in length and intensity, and vocal responses were elicited in different phases and volumes of the quiet breathing cycle. A velocity threshold was used to distinguish prephonatory adjustments from the cyclical movements of the chest wall that are characteristic of quiet breathing. The results suggest that a variety of prephonatory kinematic events can occur prior to initiation of vocalization in response to a stimulus. Further, prephonatory movements appear to be adaptive in that they are influenced by the length of the utterance to be spoken and the respiratory volume at the time of voice initiation.