A dynamic analysis of reiterant speech production

Abstract

Speaking, like other biological activities, emerges from a neuromuscular basis of high dimensionality as a coherent pattern of articulator motions. What form, if any, does such coherence take and how might it be rationalized? Conventional analyses of articulatory motion are not always informative. Here we use the tools of qualitative dynamics, particularly phase portrait techniques [cf. J. A. S. Kelso and E. V. Bateson, J. Acoust. Soc. Am. Suppl. 1 73, S67 (1983)] to analyze articulatory gestures from an experiment in which speaking rate and stress are naturally varied. We show that the strong relationship between a gesture's amplitude and peak velocity may be accounted for when movements are analyzed in an action (energy × duration) versus amplitude performance space. The action for a given gesture (associated with consonant‐vowel and vowel‐consonant transitions) and for a given speaker scales to (amplitude)2. This finding suggests (1) that stiffness is a key dynamic parameter of the articulatory system, and (2) that an elastic similarity principle may underlie the articulatory behavior of different speakers. [Work supported by NIH, BRSG, and ONR.]