Vibration of the vocal folds observed using a high-speed movie system with consumer digital video camera

Observing vibration of the vocal folds is essential to find causes of hoarseness. We assembled the high-speed movie system from a consumer digital video camera (EXILIM PRO EX-Fl, Casio Computer Co., LTD., Tokyo) and a conventional rigid laryngeal endoscope. This system enables us to observe each vocal fold vibration at a frame rate of 1, 200 images per second. We examined the vocal folds of 10 healthy subjects and two patients with hemilateral vocal fold paralysis with our system. The high-speed movies were saved in the camera as MOV format files. On slow playback of the movies and kymographic images constructed from the movie files, the vocal fold vibrations of healthy subjects showed regularity, symme-try, complete glottal closure, normal amplitude and normal mucosal waves. However, those of the sub-jects with vocal fold paralysis showed irregularity, asymmetry, incomplete glottal closure, abnormal am-plitude and abnormal mucosal waves. Our system will be useful for a routine clinical examination of the vocal folds.