Vortical Flow Field during Phonation in an Excised Canine Larynx Model

Abstract

Objectives-To more fully understand the mechanisms of vocal fold vibration and sound production, we studied the velocity flow fields above the folds. Such velocity fields during phonation have not been reported in the literature. Methods-Using the particle image velocimetry method for 3 excised canine larynges, we obtained the velocity fields in the mid-membranous coronal plane during different phases of phonation. The velocity field was determined synchronously with the vocal fold motion recorded by high-speed videography.Results-The results show that vortices occur immediately above the vocal folds and that the location and shape of the vortices depend on the phase of the phonation cycle. Consistent vortical structures found included starting vortices, Kelvin-Helmholtz vortices, entrainment vortices, and vortices directly above the folds during the divergent glottal stage.Conclusions-These vortical structures were consistently found during specific phases of the glottal cycle for 3 canine larynges that significantly varied in size. This consistent behavior suggests that the vortices may be important for both vibration and sound production; however, further study is needed to prove this. The clinical significance of these vortices is discussed.

On the acoustical relevance of supraglottal flow structures to low-frequency voice production

“…Previous studies showed that the physical model exhibited qualitatively similar vibratory pattern (Zhang et al, 2006b(Zhang et al, , 2009) and supraglottal flow field pattern (Neubauer et al, 2007;Drechsel and Thomson, 2008) to that observed in excised-larynx (Khosla et al, 2007) and in-vivo canine models (Dollinger et al, 2005). In general, the vocal fold models exhibited vibratory patterns (e.g., onset frequency and pressure, pressure-flow relationship, vibration amplitude, and flow modulation, etc.)…”

The influence of material anisotropy on vibration at onset in a three-dimensional vocal fold model

“…Another aspect of the fluidstructure interaction that may be oversimplified in this study is the use of a one-dimensional flow model. More realistic flow models need to be used so that the effects of realistic flow features (e.g., flow curvature effects, asymmetric flow pressure, and vortex shedding; Erath and Plesniak, 2006;Neubauer et al, 2007;Khosla et al, 2007) can be considered. For example, it is possible that non-FM modes may participate in synchronization if a non-uniform flow pressure distribution along the AP direction is allowed, which may happen in realistic phonation.…”

Computational modeling of phonatory dynamics in a tubular three-dimensional model of the human larynx

“…Intraglottal vorticity-velocity interaction, glottal jet structure, and its transition to turbulence are all demonstrated to be highly three-dimensional (3D) (McGowan, 1988;Neubauer et al, 2007;Triep et al, 2005;Triep and Br€ ucker, 2010;Zheng et al, 2011b). The 3D effects are clearly observed in the supraglottal region in both the experimental Triep and Br€ ucker, 2010;Khosla et al, 2007;Khosla et al, 2008) and numerical studies (Zheng et al, 2010b;Mattheus and Br€ ucker, 2011). The asymmetric flow deflection in the 3D models is also observed to be different from the 2D models.…”