The influence of geometrical and mechanical input parameters on theoretical models of phonation

Abstract

The influence of initial aperture and mechanical properties on the onset pressure thresholds and oscillation frequencies is experimentally assessed on a deformable vocal fold replica in case of strong and weak acoustical coupling. The mechanical replica enables to vary the initial aperture while mechanical properties are maintained and therefore to mimic abduction and adduction gestures of human phonation. Depending on initial conditions (geometrical, mechanical and acoustical) one or two oscillation regions are experimentally found for which important differences are observed for both oscillation onset pressure thresholds and oscillation frequencies. Measured onset pressure thresholds are used to validate the outcome of a theoretical model of phonation using a reduced mechanical model. The applied coupling stiffness in the theoretical model is estimated from the measured frequency response instead of imposed by an 'ad-hoc' criterion. The variations in coupling stiffness result in a qualitative agreement between predicted and measured values for all assessed experimental conditions. In addition, the Young's modulus of the replica is qualitatively estimated to be within the range observed 'in-vivo'.