Direct measurement of glottal flow waveform in an excised K9 larynx with a vocal tract

Abstract

False vocal folds (FVF) or ventricular folds have been shown to impact the vibration of the true folds. Using computational and experimental models to examine the aerodynamic and acoustic effects the FVF, previous studies have shown that the presence of FVF lowers the phonation threshold pressure, the overall intraglottal pressure distribution, and enhances intraglottal vortical structures. However, the full effect of the FVF on the glottal flow waveform has never been measured in a tissue model of the larynx. Therefore, the objective of this study was to evaluate the impact of FVF on the glottal flow waveform in an excised canine model. A vocal tract model was placed over the larynx, and direct velocity measurements were taken at the glottal exit using tomographic particle image velocimetry. Measurements were taken with a systematic change of the FVF constriction and integrated to calculate the air flow waveform. The results show that a restriction above the folds increased the overall flow rate (dQ/dt) and change the maximum flow declination rate (MFDR). The 3-D measurements at the glottal exit can also be used to validate previous computational studies on how the vocal tract affects the phonation mechanism. The clinical significance of these findings will be further discussed.