Dynamic digital image correlation of a dynamic physical model of the vocal folds

An experimental study of the vibratory deformation of the human vocal folds was conducted. Experiments were performed using model vocal folds made of soft silicone rubber, and an air supply system. The model self-oscillated at fundamental frequencies and flow rates typical of the human folds. Time-averaged mass flow rates and transglottal pressures were measured along with the sound pressure upstream of the orifice. The deformation of the vocal fold was measured using a high-speed threedimensional digital correlation system. The imaging set-up is composed of a high-speed digital camera and a prism beam splitter allowing two images to be obtained from different viewpoints in every image frame. Commercially available digital image correlation software was used to analyze the images, and to calculate the strain fields at the vocal fold superior surface. Results were obtained for vocal folds made of isotropic material and two different vocal fold lengths. The deformed shape of the model vocal folds, strains on the superior surface, and the time-varying vocal fold wall displacement were obtained.