Three-Dimensional Experimental Study of Glottal Jet Dynamics in Phonation

We present the first three-dimensional fluid flow analysis in the intraglottal and supraglottal space in a 1:1 physiologically accurate model of the human pharynx. The model is created using geometrical context from an anatomically accurate model. The test section is prepared using PDMS. Assuming a quasi-steady flow, a steady flow of water-glycerin mixture for matching the refractive index is used. We test three configurations of the intraglottal section based on three key phases of a healthy vocal fold vibration – converging (opening), straight (open) and diverging (closing). Each configuration is tested for 3 different flow rates. Shake-the-box (STB) algorithm is used to compute the particle tracks from images captured using a four-camera setup. The particle tracks are propagated through an in-house binning workflow to extract flow features. We uncover the three-dimensional flow structures in the subglottal, intraglottal and supraglottal region and the variation of these in three distinct phases of a typical vocal fold oscillation. Flow information is analysed by extracting the vorticity, lambda ci, and q-criterion fields. These observations will enable a deeper understanding of the formation of the glottal jet.