Lip-larynx coordination in speech: effects of mechanical perturbations to the lower lip.

This experiment investigates the coordination between the larynx and the lips and jaw in voiceless consonant production using an experimental paradigm where a mechanical perturbation is applied to an articulator. Three subjects received unexpected perturbations to the lower lip during the transition between the first vowel and the first stop in /i'pip/. Movements of the upper articulators (lips and jaw) were recorded using an optoelectronic technique. Laryngeal responses were monitored using transillumination; intraoral pressure and the acoustic signal were also recorded. Results showed that laryngeal abduction was delayed following lip perturbation and that the duration of the laryngeal adduction gesture was lengthened. The oral movements toward closure of two of the subjects were modified and all subjects showed modification of the oral release movements in the perturbed conditions. All subjects showed an increased movement velocity and displacement of the upper lip, lower lip, and jaw in the oral opening phase. First trial compensation, however, was not observed in two of the three subjects. The results are discussed with respect to the speech perturbation literature and the notion of coordinative structures.