Aerodynamic vocal functions under a systematic change in intensity.

Abstract

This paper reports on the relation between voice intensity I*[dB] and mean airflow rate U [cm3/s] during the sustained phonation of a vowel-like sound. In the experiment each subject was asked to increase the intensity of phonation in gradual steps from a “comfortable” level to higher degrees; without exceeding a level where discomfort would have resulted. During this process the fundamental frequency (F0) was kept constant. A total of 18 sets of data were obtained from 4 females and 7 males. Values of intensity and airflow rate were plotted on an I* vs. U* display, where U* indicates dB representation of U, i.e. U* =20 log (U/U0), where U0=1cm3/s. The relationship between I* and U* were represented both by a single line, and several line segments (up to three). Each line is represented by I* =AU* +B, and values of A were examined statistically for both -single and three line approximations. A value of A=2 was observed most frequently for the single line approximations, regardless of female/male distinction. For the three line approximations, the median of A was 1.5, 2.9, and 2.0, as obtained for low, edial, and high intensity regions, respectively. Overall patterns for the three line approximations were also examined, and it was found that S-shaped patterns appeared most frequently. These results will be useful for discussing the laryngeal control during the phonation.