Experimental analysis for the contribution of tooth vibration to production of sibilant /s/ ∼ measurement of sound and vibration ∼

Sibilant /s/, one of unvoiced sounds, is believed to be produced by flow turbulence provoked by the impingement of a jet to anterior teeth. Although it would be possible that the impingement of a jet as well as pressure fluctuations behind the anterior teeth associated with flow turbulence make anterior teeth vibrate, whereby contributing to the production of sibilant /s/, no studies have focused on this aspect. The present study is designed to investigate the possibility that the vibration of teeth contributes to the production of sibilant /s/. A morphologically simplified model of an oral cavity is fabricated. An air is steadily delivered at 45 L/min to the model to produce aeroacoustic sounds. Sound and vibration of teeth (obstacle wall) are measured simultaneously with a microphone and the Michelson interferometer. The spectrum analysis showed two peaks in the sound at 1,300 and 3,500 Hz, and one peak in the wall vibration at 3,500 Hz. An association of the peak at 3,500 Hz between the sound and wall vibration suggested that this sound is produced as a result of wall vibration. Experiments exhibited a decrease in the sound amplitude with an increase in thickness (rigidity) of teeth (obstacle wall). Those results demonstrated potential of the proposed method for exploring the production mechanism of sibilant /s/ and possibility of the contribution of teeth vibration to the production of sibilant /s/.