| This thesis is concerned with an experimental study of the flow through a dynamic mechanical model of the larynx. The model was built in order to investigate the effect of motion of the glottal walls on the volumetric flow rate, transglottal pressure, and flow patterns in the glottal region.;The production of voice is depends on the flow of air through the glottis, the shape of which is time-dependent. Most experimental studies reported so far used static replicas of the vocal folds in order to determine pressure-flow relationships. Only a limited number of experimental studies on moving replicas of the vocal folds have been reported, and they are generally restricted to simplistic motion.;In order to accurately reproduce more realistically the motion of the vocal folds, a scaled dynamically similar experimental apparatus was built that permits the variation of both the glottal opening and angle for the present study.;The motion of the model can be driven at different frequencies. The flow is driven at a constant overall pressure, which can be adjusted within a wide range of values. Both the transglottal pressure difference and flow rate were measured over the motion cycle. Flow visualization was performed for a wide range of experimental conditions.;The measurements show that both the flow rate and transglottal pressure are affected by the frequency of the oscillation. The inertance of air in the trachea and vocal tract, together with the unsteady flow rate, produce a fluctuation of pressure both upstream and downstream of the glottis, which is reflected in a frequency-dependent transglottal pressure drop. The flow resistance was found to depend on the frequency of motion. The flow visualization results indicate that the flow can be laminar, transitional, and turbulent, depending not only on the shape of the glottis and the lung pressure, but also on the frequency of motion. The flow patterns for dynamic cases present significant differences compared to those obtained for the corresponding static cases.;The results raise questions concerning the validity of the quasi-steady assumption, and provide initial information on the dependence of acoustically-related glottal flows on vocal tract inertance and glottal wall motion. |
