Simultaneous Measurement of Subglottal and Supraglottal Pressure Variations
Shizuo Hiki, Y. Koike, Hideo Kohka Takahashi · The Journal of the Acoustical Society of America · 1970
The short-term variations of the subglottal and supraglottal pressures during phonation were measured simultaneously, utilizing two identical miniaturized solid-state pressure transducers [Y. Koike, J. Acoust. Soc. Amer. 46, 96–97 (1969)] inserted into the trachea and the pharynx through the nostrils, to obtain a direct estimation of the waveform of the pressure difference across the glottis at a close distance. The magnitudes of these short-term variations and the phase relations between them were analyzed, and their effect on the vibration of the vocal folds is investigated on the basis of a mechanical model of the laryn. Simultaneously with the above measurements, the vibration of the outer skin surface of the trachea was picked up with a 14-in.-diam condenser microphone coupled with a rubber pipe. The resulting waveform displays considerable agreement with that of the subglottal pressure, and it is shown that the contact microphone output may be applicable to the study of the detailed properties of the amplitude and phase spectrum of the subglottal pressure variation or of the glottal sound by taking into account the transmission characteristic of the tracheal wall and the acoustic impedance of the trachea. These characteristics can be calculated from the results of the above measurements. [This study was partially supported by a USPHS grant and by NASA contract.]