Optimized transformation of the glottal motion into a mechanical model.

During phonation the human vocal folds exhibit a complex self-sustained oscillation which is a result of the transglottic pressure difference, of the characteristics of the tissue of the folds and of the flow in the gap between the vocal folds (Van den Berg J. Myoelastic-aerodynamic theory of voice production. J Speech Hearing Res 1958;1:227-44 [1]). Obviously, extensive experiments cannot be performed in vivo. Therefore, in literature a variety of model experiments that try to replicate the vocal folds kinematics for specific studies within the vocal tract can be found. Here, we present an experimental model to visualize the fluid dynamics which result from the complex motions of real human vocal folds. An existing up-scaled glottal cam model with approximate glottal kinematics is extended to replicate more realistically observed glottal closure types. This extension of the model is a further step in understanding the fluid dynamical mechanisms contributing to the quality of human voice during phonation, in particular the cause (changed glottal kinematics) and its effect (changed aero-acoustic field). For four typical glottal closure types cam geometries of varying profile are generated. Two counter rotating cams covered with a silicone membrane reproduce as well as possible the observed glottal movements.