Quantitative study of mucosal wave via videokymography in canine larynges

Objectives: Vocal fold mucosal wave movements are thought to be important i n determining voice characteristics and quality. To see these movements, hi gh-speed cinematography and videostroboscopy have been used clinically; how ever, these techniques have disadvantages that make them impractical for qu antitative measurement of mucosal wave movements. This study explored the f easibility of using line-scan cameras for mucosal wave analysis. Methods: A n excised larynx bench model was used to examine the effects of elongation and changes in subglottal pressure on the amplitude, frequency, and phase d ifference of vocal fold mucosal movements as calculated from line-scan imag es. Results: The data showed a positive and linear relationship between an increase in subglottal pressure and amplitude of the mucosal wave; elongati on of the vocal folds appeared to decrease the amplitude of mucosal wave up heaval at each level of subglottal pressure. Similarly, increase in subglot tal pressure had a positive and linear relationship with increase in freque ncy of vibration; elongation of the vocal folds further increased the frequ ency at any given subglottal pressure. Phase difference between the movemen ts of the upper and lower margins of the mucosal lips was estimated and did not appear to be significantly affected by changes in subglottal pressure and elongation. Conclusion: The data presented in this study are consistent with relationships that we would expect to be true from currently accepted models of vocal fold vibration.