Coordination between posture and phonation in vocal effort behavior.

BACKGROUND Postural correlates of vocal effort are rarely described in the literature, while they are extensively dealt with in speech therapy. OBJECTIVES This study aims at determining whether body movement is a side effect of vocal effort or an integral part of communication effort behavior. The answer to this question is mainly based on correlations between posture and phonation. METHOD Twenty healthy subjects participated in this study. They had to communicate with a listener under 3 conditions requiring different levels of vocal effort. RESULTS The vocal parameters increased and confirmed that the subjects had made a vocal effort. The kinematic parameters (amplitude and duration of body movement) increased with vocal effort. Lastly, vocal and kinematic characteristics were significantly correlated. CONCLUSION The close correlation of posture with vocal production shows that movement is not a mere consequence of vocal effort. Posture and voice are coordinated in communication behavior, and each body segment plays its specific role in the vocal effort behavior.