Fundamental characteristics of jaw movements for vowel sequence words based on a dynamic model.

Abstract

Jaw movements in the production of vowel sequences were analyzed by means of the framework of dynamic model. An instrument to observe the jaw movements using an optical spot position sensitive detector was developed. Utilizing this instrument, the jaw movements in the production of meaningless three-mora Japanese vowel sequence words were observed. As the basic analysis, the jaw opening for each vowel and the time constant for each transition at the extremely slow speaking rate were analyzed. Afterwards, the target value of jaw opening at the fast speaking rate was estimated. In this study, the time function of the observed jaw movement was approximated by the response of the critically damped linear second order system driven by the step function, whose amplitude represents the target value of the jaw opening for each vowel. Results obtained in this study suggest that the target value of jaw opening for each vowelshould be different depending on the speaking rate and the word-internal vowel position. However, for the tendency concerning the difference in the target values caused by the adjacent vowels, common characteristics for two subjects of this study were not observed.