Effect of Mechanical Properties on the Dynamics of Self-Oscillating Synthetic Vocal Folds

Abstract

This study focuses on the measured changes in dynamic behavior exhibited by eight synthetic vocal fold models with varying mechanical properties. Uniaxial tensile testing was conducted to determine changes in mechanical properties between materials made from silicone rubber and polydimethylsiloxane with varying mixing ratios. The results of the mechanical testing showed that the elastic modulus, E, varied from 20.6 to 437.4 kPa, the measured Poisson ratios, ν, spanned the range of 0.43–0.48, and the density, ρVF, varied from 0.86 to 1.02 g/cm3 across the eight samples. Vocal fold models were dynamically tested using a custom-built experimental setup that supplied a heated and humidified airflow to the synthetic vocal folds. The resulting sounds were recorded and analyzed to identify the change in fundamental frequency which spanned 66.8 to 342.6 Hz across the eight samples. In addition, a mathematical aeroelastic model of phonation was implemented to further investigate the relationship between the mechanical properties and phonation frequency. Finally, a proof-of-concept magnetic actuation method was demonstrated using magnetic elastomers to deform the synthetic vocal folds through the use of an electromagnet.