Effect of speaking rate on jaw movements in vowel sequences.

Abstract

The purpose of this experiment is to study the effect of the speaking rate on the articulatory movements of jaw. Two subjects read a list of nonsense words of the form /V1 V2 V3/, where V1 and V3 were all possible combination of /i, o, e/ and V2 was one ofthe five vowels /i, u, o, a, e/. We measured articulatory dynamics (displacement, transition time and velocity) of jaw movements at the two speaking rates and estimated dynamic characteristics of jaw articulatory system. The results of this study show that the adjustments of speaking rate were achieved by the different strategies between the subjects: with the increase in speaking rate, (1) the velocity of movement did not change, but the articulatory displacement was decreased, and (2) the velocity was increased and the displacement did not vary. The effect of speaking rate on the magnitude of articulatory efforts was clearly observed during the closing movements. The subject who demonstrated rapid movement at the fast speaking rate might increase the articulatory force in the jaw muscular system.