Traveling Wave in Vocal Fold Vibration

Abstract

The authors reviewed the literature on the mode of vocal fold vibration, which has been considered to be a transmission of the mucosal wave upward from the lower surface of the vocal fold. Many high-speed cinematographic or stroboscopic images have been obtained from the supraglottic area, but the vibratory mode of the lower surface of the vocal fold remains unclear. We observed vocal fold vibrations from the infraglottic as well as the supraglottic areas with high-speed cinematography and found that:
1) Traveling waves moved upward from the mucosal upheaval or inside it. That is, the mucosal upheaval vibrated with an earlier phase than any other portion of the vocal fold.
2) In the closing phase, the lower lip became a free edge and moved upward. After contract of the lower lips of both sides in the midline, lower lip became the upper lip and moved upward. At the time of contact, the reflection wave, identified as the lower lip from the infraglottic image, retracted laterally rapidly.
3) At the end of the opening phase, the lower lip of the next cycle began to move medially.
4) The mucous membrane outside of the mucosal upheaval did not virbrate actively.
5) On the basis of these findings, we tried to diagram the frontal sections of the vibrating vocal fold in different phases.