Phase Transitions in Speech Production and Their Perceptual Consequences

Abstract

Previous work shows that the relative phasing of articulatory events varies little across two levels of speaking rate and stress. But, one may ask, varies little with respect to what? A methodology is required that differentiates articulatory patterns as they evolve in time. With this aim, subjects were instructed to say /ip/ or /pi/ repetitively, at increasing speaking rates, while monitoring their glottal and lip movements. For /pi/, the observed interarticulatory phase relationships did not depend on speaking rate. For /ip/, relative phasing often changed markedly, suggesting that loss of stability underlies articulatory change (a phase transition). In two follow‐up perceptual experiments, listeners appeared to judge the consonant's syllable affiliation on the basis of interarticulator relative phase, and did so in a “categorical” manner. These findings, interpreted in light of a theoretical model based on synergetics [Kelso et al., Physics Scripta 35, 79–87 (1987)], may help resolve controversies conc...