Numerical Analysis of Effects of Transglottal Pressure Change on Fundamental Frequency of Phonation

Abstract

Objectives:

In humans, a decrease in transglottal pressure (P_t) causes an increase in the fundamental frequency of phonation (F₀) only at a specific voice pitch within the modal register, the mechanism of which remains unclear.

Methods:

In the present study, numerical analyses were performed to investigate the mechanism of the voice pitch-dependent positive change of F₀ due to P_t decrease. The airflow and the airway, including the vocal folds, were modeled in terms of mechanics of fluid and structure.

Results:

Simulations of phonation using the numerical model indicated that P_t affects both the average position and the average amplitude magnitude of vocal fold self-excited oscillation in a non-monotonous manner. This effect results in voice pitch-dependent responses of F₀ to F_t decreases, including the positive response of F₀ as actually observed in humans.

Conclusions:

The findings of the present study highlight the importance of considering self-excited oscillation of the vocal folds in elucidation of the phonation mechanism.