Abstract
It is well known that head moves rhythmically and coordinately with mandible during masticatory movement. The present study investigated whether the head-neck behavior can also be influenced by the jaw movement during the production of voice. Using a video-scanning method, the head-neck and jaw motions were analyzed in 16 healthy adults phonating two types of syllables, /ata/ and /aka/ in Japanese. The subject was asked to phonate 10 times in each syllable following after the sample voice. The order of syllables was randomized. The voice via a microphone was converted into LED signals and recorded with the motion signals from the LEDs placed around the facial and neck regions. The head-neck movement was divided into two hinge movements, the head movement around an atlanto-occipital joint and the neck movement around a cervical-spinal joint, respectively. The head extension and the neck flexion synchronized for the jaw opening were observed in all subjects. The motion wave of 500 ms period before the starting point of the vocal signal was selected and averaged 10 times for analysis. The amounts of movement were compared between the phonation of /ta/ and /ka/. There was a higher degree of correlation between the head extension and the jaw opening than that between the neck flexion and the jaw opening. The neck flexion and the jaw opening were started at about the same time, while the head extension was always later than these motions. From these findings, it was supposed that the head behavior was closely related to the jaw movement, while the neck did not depend on it during voice production. [Jpn J Physiol 55 Suppl:S172 (2005)]
