Effect of medial surface shape on voice production in a MRI-based three-dimensional phonation model

Abstract

Our previous studies using simplified vocal fold geometry have shown that medial surface shape, particularly the vertical thickness, has an important effect on the closure pattern of vocal fold vibration. The goal of this study is to investigate if similar effect can be observed for medial surface shape that occurs in realistic human phonation, using a parametric MRI-based three-dimensional vocal fold model. Manipulation of medial surface shape is achieved through a two-level control of the superior and inferior portion of the medial surface, based on experimental observations. Simulations show that, in general, both superior-medial bulging and inferior-medial bulging of the medial surface, which leads to an increased vertical thickness and a more rectangular glottal configuration, increase the closed quotient of the vocal fold vibration. Changes in medial surface shape also have significant effect on the phonation threshold pressure. This effect of the medial surface shape varies significantly across larynges, indicating the important effect of subject-specific laryngeal geometry. The results point to the importance of taking into consideration of the medial surface shape in clinical management of voice disorders. [Work supported by NIH.]