Postural entrainment by vocal effort in singing and speech

This study assesses the interaction of the postural control system and the production of expressive vocal behavior during speech and singing. In particular, we focus on the head, whose motions have been implicated for both postural control and spoken language production. How does head motion behavior simultaneously serve posture control and linguistic communication during vocalization? This study examines the interaction of these two subsystems by measuring the effects of different levels of vocal effort (loudness) on speech and singing. We show that as vocalizations becomes louder the correspondence between measures of head motion and speech acoustics become less complex and better coordinated spatiotemporally. In order to show that the head-voice coordination indeed concerns posture control, the same coordination effects are demonstrated for time-varying measures of body posture, measured with force plates under each of the performer's feet.