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Bifurcation phenomena in vocal fold vibrations - experiments in vitro
Horáček, Jaromír ; Švec, J. ; Veselý, Jan
The study presents experimental investigations focused on monitoring of the non-linear vibration effects, especially bifurcation phenomena in the vibration of human vocal folds. The experiments were performed with excised human larynges excited by airflow. Sudden changes between different regimes of the vocal fold vibration were observed when smoothly changing the tension of the vocal folds. The study reveals further details on the nature of sudden changes between voice registers. The results also point out the possible relationship between regular (physiologic) and irregular (pathologic) vocal fold oscillations.
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Steady and unsteady flow over a profile in a channel
Honzátko, R. ; Horáček, Jaromír ; Kozel, K.
The work deals with numerical solution of 2D inviscid incompressible flow over the profile NACA 0012 in a channel. The finite volume method in a form of cell-centered scheme at quadrilateral mesh is used. Governing system of equations is the system of Euler equations. Numerical results achieved at H-mesh and C-mesh are compared. The work presents computation of the steady states of the flow and also unsteady flow influenced by the prescribed oscillating behaviour of the profile.
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Model of vocal fold oscillation in viscous fluid flow
Horáček, Jaromír
A vibrating element on an elastic foundation in the wall of a channel conveying air approximates the vocal fold oscillations. The viscous incompressible 1-D fluid flow theory is used and a generally defined shape of the vocal fold is considered. The numerical solution yields the instability thresholds, which are close to the known physiological data for phonation thresholds. The viscosity is important for very small opening of the glottis where its effect on instability boundaries increases.
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