Quantitative measurement of mucosal wave by high-speed photography in excised larynges.

The movement characteristics of mucosal waves of the vocal fold are important components in normal phonation. Quantitative studies of the mucosal wave have used stroboscopic techniques from a supraglottic view. The current study measured displacement of mucosal epithelium during experimental phonation by using high-speed photography from an infraglottic view. Effects of thyroarytenoid contraction, increased mean airflow rate, and variation of vocal fold length were examined in canine larynges. Top and bottom vocal fold "lip" amplitude, fundamental frequency, and phase difference were the dependent variables examined. Thyroarytenoid contraction increased the amplitude of the top and bottom lips, decreased the fundamental frequency, and increased the phase difference. Increase in airflow through the glottis decreased the top lip amplitude and phase difference and appeared to increase the fundamental frequency and to decrease the bottom lip amplitude. Vocal fold lengthening decreased the bottom lip amplitude and increased the fundamental frequency and appeared to decrease the top lip amplitude and phase difference.