Structural Constitutive Characterization of the Vocal Fold: Modeling the Fibrous and the Interstitial Matrix Proteins

The extracellular matrix (ECM) of the human vocal fold is a highly specialized soft connective tissue with a layered microstructure that is optimally tuned for vibration and sound production in response to a unique set of biomechanical stimuli in vivo, including oscillation at amplitudes up to 3–4 mm at magnitudes of acceleration > 200g and at high frequencies (> 100Hz). The vocal fold ECM, commonly called the lamina propria or mucosa, consists of biomacromolecules of two major classes distributed in different densities: (1) fibrous proteins including collagen and elastin fibers that are denser in the deep layers of the ECM, and (2) interstitial proteins like glycosaminoglycans and structural glycoproteins that are scattered throughout the entire ECM [1,2]. Nonlinear viscoelastic response of the vocal fold ECM under different loading conditions has been reported, including strain rate-dependence and hysteresis of tensile stress-strain curves, and nonlinear stress-strain behavior under large-strain shear [3,4].