ENDOSCOPIC IMAGING OF VOCAL FOLD VIBRATIO N - ULTRA-HIGH-SPEED DIGITAL CINEMATOGRAPHY WITH DIFFERENT SYSTEMS

Vocal fold vibration patterns during phonation are presented with diff erent digital imaging systems. With newly developed technical equipmen t color images up to 1000 digital images/s were obtained without light intensifying enhancement techniques via rigid and flexible endoscopy. With this color high-speed system, morphologic structures, such as sm all blood vessels, were visualized in high-resolution quality as a res ult of additional color information. In another system, zooming of end oscopic pictures via pixel interpolation algorithms provided full-moni tor presentation of vocal fold vibratory patterns. This system allows PC-based synchronization with microphone and electroglottographic sign als in a frame-by-frame technique. Although only processing gray scale images, analyses of dynamic changes in modes of vibration were facili ated by the higher frame rate recording of up to 2000 frames/s and, in addition, they display corresponding analog signals. Both methods pro vide clinically important information. Furthermore, we demonstrated ir regular vocal fold vibration patterns in a healthy adult volunteer. In this experiment, the irregular vibratory modes were induced by volunt arily applying asymmetric vocal fold tension. The asymmetric vocal fol d vibration pattern resulted in (functionally induced) roughness of th e voice as predicted by computer models of asymmetric vocal fold vibra tion. Digital highspeed cinematography proved to be a highly promising technique in the analysis of dysphonia and provided physiological exa mples that could be compared with models of coupled nonlinear oscillat ors.