Entrainment by vocal effort: Coordination in postural control and speech production

Abstract

The biomechanical coupling between the systems implicated in speech production, postural control, and respiration suggests that some degree of coordination in the form of postural entrainment should take place given excessive task demands in the speech domain, as has been previously reported [Vatikiotis-Bateson, et al., (2009) Proceedings of ESCOM 2009]. In this context, this work assesses the time-varying coordination and entrainment among multiple components of the postural control system that result from the modulation of vocal effort level in both read and spontaneous speech. Correlation map analysis is used to quantify the coordinated patterns of interaction between speech acoustics and a variety of related physical systems, including lower body postural configuration (center-of-pressure calculated from force plate measurements), head motion (measured with OPTOTRAK), and visual motion (optical flow from video). Cross-correlation analysis of the measured signals shows that modulation of vocal effort leads to both qualitative and quantitative shifts in the coordinative dynamics of the system, uniformly resulting in better spatiotemporal coordination and reduced rhythmic pattern complexity as vocal effort is increased.