Frequency response of synthetic vocal fold models with linear and nonlinear material properties.

Abstract

Previous studies have shown the importance of cricothyroid muscle activation in altering fundamental frequency of the human voice. Other studies have explored the nonlinear stress‐strain properties of human vocal fold tissue and shown that this also influences vibration frequency. Synthetic models have been and are currently being used to characterize behavior of the human vocal folds. To date, the models have used materials with essentially linear stress‐strain properties. The purpose of this research study was to investigate the frequency response of synthetic models fabricated with linear and nonlinear materials as a function of anterior‐posterior stretching (as in cricothyroid muscle activation). Methods are described for fabrication of both materially‐linear and nonlinear vocal fold models. The mechanism for applying anterior‐posterior stretching is described. Onset pressure and fundamental frequency data are given for linear and nonlinear models at 1‐mm stretch (about 6% strain) intervals up to 10 mm (about 60% strain). Tensile test results show stress‐strain properties for both models, and data are compared with similar tests performed using excised human vocal folds. [Work supported by NIH.]