High-speed imaging analysis of anterior-posterior asymmetry of vocal fold vibration

High-speed imaging directly observed the anterior-posterior asymmetry of vocal fold vibration. This study performed quantitative analysis and comparison to the fundamental frequency measured by high-speed imaging and sound recording in 11 excised canine larynges. Three sets of subglottal pressure, including 10 cmH₂O, 20 cmH₂O, and 30 cmH₂O were applied. Using Lagrange interpolation and Canny image edge detection, the glottal area time series was obtained, and then the vibratory fundamental frequency was derived. The fundamental frequency increased with the subglottal pressure. The correlation relationship between the fundamental frequencies obtained by these two measurement methods had been investigated and the correlation coefficient above 0.9 was found, indicating the high correlation. Therefore, the results have shown that high-speed imaging technology could direct measure vocal fold vibration and provide valuable tool to reveal physical mechanisms of laryngeal activities. The vibration amplitudes of the vocal fold linear structure 25%, 50%, 75% locations show that vocal fold vibration is anterior-posterior asymmetry and the asymmetry vibration is more apparent under low subglottal pressure.