Abstract:

Knowledge of the mechanical properties of vocal fold tissues is necessary for the constitutive modeling of vocal-fold mechanics. Assuming transverse isotropy in a linear, elastic continuum model of vocal-fold tissues, five material constants are needed to solve the constitutive equation [D. A. Berry and I. R. Titze, J. Acoust. Soc. Am. 100, 3345--3354 (1996)]. Among these constants, Poisson's ratios can be estimated by assuming tissue incompressibility, while the shear moduli and Young's moduli are related to one another. A parallel-plate rotational rheometer was used to examine the dynamic shear behavior of human vocal fold tissues and three commonly used phonosurgical biomaterials (bovine collagen suspension, absorbable gelatin suspension, and human subcutaneous fat). In oscillation at 0.1--10 Hz and at 37 (degrees)C, the magnitude of dynamic shear modulus of vocal fold mucosa was on the order of 100 Pa, close to that of fat. The shear modulus magnitudes of collagen and gelatin were an order of magnitude higher. These results suggest that the use of fat for vocal-fold augmentation surgery is more conducive to phonation, because of its similarity to the vocal-fold mucosa in shear stiffness. [Work supported by NIH.]