Visualization and High-speed Piv Measurements of the Flow Downstream a Dynamic Mechanical Model of the Human Vocal Folds

The intention of the present study is the detailed analysis of the unsteady vortex dynamics downstream the human glottis during phonation at typical fundamental frequencies of about 120 Hz (for men). A hydraulic respiratory mock circuit has been built-up including a three-times up-scaled realistic dynamic model of the vocal folds. Time-resolving flow measurements were carried out downstream the glottis by means of high-speed Particle-Image Velocimetry (PIV). The function of the human glottis is reproduced by two counter-rotating cams each of which is covered with a stretched silicone membrane. The 3-D geometry of the cams is designed such that the rotation leads to a realistic time-varying motion and profile of the glottis and waveform of the glottal cycle. The velocity field is captured with high spatial and temporal resolution to investigate the unsteady vortex dynamics of the periodic jet entering into the vocal tract. The results help to understand the vorticity interaction within the pulsating jet and the consequently generated noise in human voice. In addition, changing the 3-D contours of the cams in different specific ways enables to investigate basic pathological differences of the glottis function and the resulting alterations of the velocity and vorticity field in the vocal tract. Fig. 1 Oblique view onto the mechanical model of the glottis and visualization of the vortex dynamics downstream in the vertical centre plane for two successive moments in the glottal cycle