Experimental and theoretical investigation of self-sustained vibration in a two-layer vocal fold model with left-right stiffness asymmetry

Abstract

The vibratory characteristics of a self-oscillating two-layer vocal fold model with left-right asymmetry in body-layer stiffness were experimentally investigated, with the goal of better understanding the relative difference in vibration amplitude and phase between the two folds. Two regimes of distinct vibratory pattern were identified. In the first regime with extremely large stiffness mismatch (larger than a factor of ten), vocal fold vibration was dominated by the vibration of the soft fold only, while the other fold was enslaved to vibrate at the same frequency. The fundamental frequency was close to that of the soft fold in a symmetrical condition. In the second regime when the left-right stiffness mismatch was reduced, both folds vibrated with comparable amplitude. In this regime, either fold can exhibit a relatively larger amplitude but the stiff fold consistently led the soft fold in phase for all conditions. The experimental results were compared to predictions from a two-dimensional plane-strain vocal fold model, and qualitatively good agreement was obtained between experiment and simulation. The clinical implications of the results of this study are also discussed. [Work supported by NIH.]