Effects of oscillation of a mechanical hemilarynx model on mean transglottal pressures and flows

This study introduces a mechanical model of the larynx for investigating dy namic aerodynamic effects of phonation. The model mimics the hemilarynx. Th e tracheal inlet section was rectangular (25-mm width, 20-mm height). The v ocal fold was fabricated with precision machinery from hard plastic with an attached oscillating plunger. A speaker assembly and audio amplifier drove the plunger, mimicking one-dimensional vocal-fold motion toward a flat wal l. The glottal shape was rectangular. The glottal diameter was well specifi ed or dynamically followed with a laser system. The air was sucked through the channel using a vacuum with controlled speed. Frequency and amplitude o f the glottis were varied. The mean pressure and mean flow data were record ed. For steady-flow conditions, the glottal gap ranged from 0.39 to 2.58 mm . The pressure coefficient for steady flow had a range of 3.1 to 1.3 for Re ynolds numbers between 300 and 9000. For oscillation conditions (a) the fre quency was varied from 75 to 150 Hz while the amplitude was held relatively constant, and (b) the amplitude was varied to 0.3 mm for a fixed frequency of 100 Hz. The results indicate that the hemilarynx model provides mean pr essure-flow data similar in form to other models with two vocal folds. Furt hermore, the dimensional and non-dimensional pressure coefficient is sensit ive to variations in glottal gap and glottal amplitude, but relatively inse nsitive to the frequency of oscillation. (C) 2001 Acoustical Society of Ame rica.