[The ultra-rapid cinematography of the larynx, its contributions in speech pathology].

The development in the medical field of high speed cinematography and its dissemination in the field of speech pathology will probably change the way we view the larynx and diagnose its disorders. So far only the stroboscope could inform us about the appearance of vocal cord vibration but with certain limitations. Indeed the wave motion of the vocal cords is really only apparent motion. It is made possible through the phenomenon of retinal persistence of images and light intermittent vocal folds set to the frequency of the voice and out of phase by a few Hertz. This technique has several disadvantages: The need for the voice to trigger the strobe light; a low number of frames per second (25 fps) recorded; frame loss for the period between unlit two flashes; limitation in the study of the upper voice spectrum (gearing). The ultra-rapid cinematography brings a big difference in design since the digital recording can shoot up to 4000 frames per second with permanent lighting of the larynx. The slow reading of short sequences permits us to view the actual movement of vibrating structures, and to analyze the behavior of the vibrator during the transitional phases of the attack, depreciation and termination of sound. The footage in high resolution permits a detailed analysis of the movements of opening and closing of the vocal cords in phonation and respiration, and the diagnosis of lesions.