空力的側面よりみた音声基本周波数の調節

Abstract

The change of Fo per unit change of transglottal pressure (dF/dP) was investigated. Since the length and stiffness of the vocal folds determine the values of dFldP, it was expected that the relationship between dF/dP and Fo would show the effects of these adjustments of the vocal folds. Six males and six females participated in this study.A specially designed tube is equipped with a mouthpiece into which the subject phonates and a shutter valve which can be partially closed during sustained phonation to create a sudden pressure increase inside the tube. The voice signal was picked up by a throat contact microphone and fed into the microcomputer simultaneously with the pressure reading inside the tube (Po). The valve was programmed to close for 300 msec during the utterance. The subjects repeated the utterance at different pitches which were raised by small steps. The computer program was designed to calculate the change of Fo per unit change of Po (dF/dP).Within the modal register, the values of dF/dP became smaller with Fo up to 200 Hz in males, and up to 250-400 Hz in females. With Fo higher than these levels, dF/dP became larger. The values of dF/dP in the modal register were smaller than those in the falsetto register. On the basis of these observations, we suggest that there is a difference between low-pitched modal register and high pitched modal register in the manner of adjustments of length and stiffness of the vocal folds.