Volumetric supraglottal jet flow field analysis in synthetic multilayered self-oscillating vocal fold model.

Recent research highlights the need for comprehensive three-dimensional (3D) analysis of laryngeal flow to better understand voice production, as traditional 2D methods fail to capture the full complexity of supraglottal jet dynamics. This study employed tomographic particle image velocimetry to capture the volume velocity flow fields in a synthetic multilayered vocal fold model. The impact of increased airway resistance from different vocal tract configurations was examined. Results indicated that adding a vocal tract reduced the maximum axial velocity and jet displacement, particularly at low subglottal pressure (Psg). Higher Psg increased both the maximum axial velocity and jet displacement. For all configurations, with and without a vocal tract, the vocal folds were observed to open at the posterior and anterior edges first, indicated by a double jet formation at the beginning of the opening phase, followed by an elongated jet during peak flow and a double jet at the posterior and anterior edges during the closing phase. Contrary to previous studies, the glottal flow waveforms became more symmetric between the opening and closing phases with higher Psg and the presence of a vocal tract. Additionally, vocal efficiency (VE) decreased while cepstral peak prominence increased with higher Psg. Overall, this study provides further insights into the influence of vocal tract configurations on the supraglottal jet and supports the correlation between glottal flow skewing and VE.