Contribution of laryngeal size to differences between male and female voice production

Abstract

In this study we investigated the effect of sex- and age-related differences in vocal fold length, thickness, and depth on voice production in a three-dimensional vocal fold model. The results showed that the cause-effect relationships between vocal fold physiology and voice production previously identified in an adult male-like vocal fold geometry remained qualitatively the same in vocal folds with geometry representative of adult females and children. We further showed that the often-observed differences in voice production between adult males, adult females, and children can be explained by differences in length and thickness. The lower F0, higher flow rate, larger vocal fold vibration amplitude, and higher sound pressure level (SPL) in adult males as compared to adult females and children can be explained by differences in vocal fold length. In contrast, the thickness effect dominated and contributed to the larger closed quotient of vocal fold vibration, larger normalized maximum flow declination rate, and lower H1-H2 in adult males as compared to adult females and children. The effect of differences in vocal fold depth was generally small. When targeting a specific SPL, adult males experienced a lower peak vocal fold contact pressure during phonation than adult females and children.

FIG. 1.

The three-dimensional vocal fold model and key geometric control parameters, including the vocal fold length L along the anterior-posterior direction, vertical thickness of the medial surface T, body-layer and cover-layer depths D_b and D_c, and the initial glottal angle α.

FIG. 2.

The mean values of selected output measures as a function of vocal fold length.

FIG. 3.

(Color online) Probability of the F0 at different values of vertical thickness T. Thinner vocal folds generally produced higher F0.

FIG. 4.

The mean values of selected output measures for vocal fold conditions representative of children, adult females, and adult males (see text for details of these vocal fold conditions).