[Influence of a repetitive commanded acoustic signal with constant frequency on jaw tapping movement]

Influence of a repetitive commanded acoustic signal with constant frequency of 1.3 Hz on jaw tapping movement was studied. 10 healthy subjects were made to perform anticipated jaw tapping movement corresponding to the signal. Jaw tapping movement with and without signal were analyzed for their opening distance and a ratio of duration of opening phase I (depressing phase), opening phase II (plateau phase), closing phase and tooth contact phase to the cycle time. 1. Opening distance in loaded tapping was shorter than that in the tapping ad lib. (P not equal to 0.01), and independently of commanded signal it became to be longer with increasement of trial numbers (P not equal to 0.01). 2. The ratio of duration of tooth contact phase in loaded tapping became smaller with increasement of the trials, although that in the tapping ad lib. became greater (P less than 0.001). 3. The ratio of duration of opening phase I in loaded tapping became greater with increasement of the trials, while that in the tapping ad lib. became smaller (P not equal to 0.01). 4. It could be interpreted that in the loaded tapping "an instant performance control" acted from the beginning of the trials and the signal might make it facile or easy to detect and confirm errors in movement.