Feedback of the Glottal Jet Flow with Supraglottal Wall Oscillations

Within this study the influence of wall oscillations in the supraglottal space on the evolution of the glottal jet is investigated. Special focus is laid on the modification of the jet evolution in space and time when small varicose vibrations are excited externally on the walls of the second constriction (ventricular folds) in the supraglottal space. The experiments are carried out in a water flow channel representing a 3:1 upscaled model of the glottal region. Instead of fixed walls in the second constriction we use silicone membranes with an internal air cushion. Sinusoidal pressure oscillations of various frequencies are excited from outside pressure lines. Flow studies show that the glottal deflection in the supraglottal space is highly sensitive to these weak oscillations, hinting on the non-linear interaction of the oscillatory waves with the shear-layer roll-up of the jet. This is known as modelocking in jet dynamics and is expected to have consequences on the sound spectrum in phonation, too.