Instability Boundaries of a Vocal Fold Modelled as a Flexibly Supported Rigid Body Vibrating in a Channel Conveying Fluid
J. Hora ́cˇek, J. (Jiří) Švec · 5th International Symposium on Fluid Structure Interaction, Aeroelasticity, and Flow Induced Vibration and Noise · 2002
A generalised leakage-flow induced vibration model for vibration onset of the vocal folds in the airflow is presented. Especially the influence of various physical properties of the vocal folds (e.g., their shape, adduction, mass and mass distribution) on the thresholds of instability is studied. A vibrating element with two-degrees-of-freedom (rotation and translation) placed on an elastic foundation and vibrating in the wall of a channel conveying air is used to approximate the vocal fold. The inviscid incompressible 1-D fluid flow theory is used. A generally defined shape of the vocal fold is considered for expressing the unsteady aerodynamic forces in the glottis. The parameters of the mechanical part of the model, i.e., the mass, stiffness and damping matrices are related to the known geometry, size and material density of the vocal folds as well as to the fundamental natural frequencies and damping known from the experiments. The numerical solution yields the natural frequencies, damping, mode shapes of vibration and the instability thresholds of the system. The calculated vibration and stability characteristics appear to be close to the known physiological data. The developed aeroelastic model is able to provide qualitative information, e.g., on conditions for a soft voice onset or for breathy voicing and could be helpful also in design of artificial voice prosthesis.