A computational study of asymmetric glottal jet deflection during phonation

Self Cite

Simulation of the phonatory flow-structure interaction has been conducted in a three-dimensional, tubular shaped laryngeal model that has been designed with a high level of realism with respect to the human laryngeal anatomy. A non-linear spring-based contact force model is also implemented for the purpose of representing contact in more general conditions, especially those associated with three-dimensional modeling of phonation in the presence of vocal fold pathologies. The model is used to study the effects of a moderate (20%) vocal-fold tension imbalance on the phonatory dynamics. The characteristic features of phonation for normal as well as tension-imbalanced vocal folds, such as glottal waveform, glottal jet evolution, mucosal wave-type vocal-fold motion, modal entrainment, and asymmetric glottal jet deflection have been discussed in detail and compared to established data. It is found that while a moderate level of tension asymmetry does not change the vibratory dynamics significantly, it can potentially lead to measurable deterioration in voice quality.

Section: B Glottal Jet Evolutionsupporting

confidence: 77%

Section: Discussionmentioning

confidence: 52%

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

Xue

Mittal

Zheng

et al. 2012

Self Cite

“…The flow was assumed to separate from the glottal wall at a point downstream of the minimum glottal constriction at which the glottal width was 1.2 times the minimum glottal width. Note that the flow separation model of this study gives only a rough estimation (Sidlof et al, 2011) of the complex flow separation pattern in asymmetric vocal fold vibration (see e.g., Zheng et al, 2011). It was chosen in this study because of its simplicity and low computational costs, which makes it possible to perform the parametric study as reported in the following text.…”

Section: Numerical Modelmentioning

confidence: 99%

Asymmetric vibration in a two-layer vocal fold model with left-right stiffness asymmetry: Experiment and simulation

Zhang¹,

Luu²

2012

Vibration characteristics of a self-oscillating two-layer vocal fold model with left-right asymmetry in body-layer stiffness were experimentally and numerically investigated. Two regimes of distinct vibratory pattern were identified as a function of left-right stiffness mismatch. In the first regime with extremely large left-right stiffness mismatch, phonation onset resulted from an eigenmode synchronization process that involved only eigenmodes of the soft fold. Vocal fold vibration in this regime was dominated by a large-amplitude vibration of the soft fold, and phonation frequency was determined by the properties of the soft fold alone. The stiff fold was only enslaved to vibrate at a much reduced amplitude. In the second regime with small left-right stiffness mismatch, eigenmodes of both folds actively participated in the eigenmode synchronization process. The two folds vibrated with comparable amplitude, but the stiff fold consistently led the soft fold in phase for all conditions. A qualitatively good agreement was obtained between experiment and simulation, although the simulations generally underestimated phonation threshold pressure and onset frequency. The clinical implications of the results of this study are also discussed.

“…In a recent study Zheng et al 2 investigated the jet deflection by a 2D numerical simulation of the glottal constriction in the case of constant glottal opening angle. They state that the large scale asymmetry of the flow downstream of the constriction is mainly influencing the jet deflection.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric glottal jet deflection: Differences of two- and three-dimensional models

Mattheus

Brücker

2011

Flow is studied through a channel with an oscillating orifice mimicking the motion of the glottal-gap during phonation. Simulations with prescribed flow and wall-motion are carried out for different orifice geometries, a 2D slit-like and a 3D lens-like one. Although the jet emerges from a symmetric orifice a significant deflection occurs in case of the slit-like geometry, contrary to the 3D lens-like one. The results demonstrate the dependency of jet entrainment and vortex dynamics on the orifice geometry and the interpretation of asymmetric jet deflection with regard to the relevance of the Coanda effect in the process of human phonation.