Glottal Airflow Resistance in Excised Pig, Sheep, and Cow Larynges

This study was to investigate glottal flow resistance in excised pig, sheep, and cow larynges during phonation at different oscillation ranges and to examine the relation of the glottal flow resistance to the laryngeal geometry and vocal fold vibration. Several pig, sheep, and cow larynges were prepared, mounted on an excised larynx bench, and set into oscillation with pressurized, heated, and humidified air. Glottal adduction was controlled by either using two-pronged probes to press the arytenoids together, or by passing a suture to simulate the lateral cricoarytenoid muscle action. Each excised larynx was subjected to a series of pressure-flow experiments, with adduction and flow rate as independent variables. The subglottal pressure, fundamental frequency, and glottal flow resistance were treated as dependent variables. The subglottal pressure, electroglottograph (EGG), and flow rate signals were recorded during each experiment. Glottal flow resistance was calculated from the pressure and flow signals, whereas the EGG signal was used to extract fundamental frequency. Preliminary data indicated a nonlinear behavior in the pressure-flow relations of these larynges with increasing glottal resistance due to increases in adduction. The average glottal flow resistance was 35.3آ آ±آ 14.8آ cmآ H2O/(L/s) for the pig, 30.8آ آ±آ 17.5آ cmآ H2O/(L/s) for the sheep, and 26.9آ آ±آ 14.9آ cmآ H2O/(L/s) for the cow.