Influence of airflow and ligament tension on the acoustics of a biomimetic larynx model

Abstract

The phonation process is a complex interaction involving the airflow from the lungs, the oscillation of the vocal folds’ tissue, and the resultant acoustics. To understand the underlying physical mechanisms, an experimental model has been designed that allow the control of flowrate and longitudinal tension of the vocal folds. A synthetic biomimetic larynx model was applied that features airflow-driven vocal folds’ oscillations. The longitudinal stiffness of the vocal folds is controlled using embedded ligament fibers. The model enables to measure aerodynamic and acoustic signals as function of airflow rate and the fiber tension. Based on the measured signals, the influence of airflow and fiber tension was statistically analyzed using the parameters F0, Psub, CPP, HNR, Shimmer, and Jitter. The statistical analysis revealed that both flowrate and fiber tension significantly influence acoustic and aerodynamic parameters. In general, the parameters showed different trends for increasing flowrate and fiber tension. Increase in fiber tension produced increasing parameters up to a maximum tension level followed by a saturation of the parameters. In contrast, the flowrate showed varying trends depending on the respective parameter. The results clearly show how flowrate and longitudinal tension control the phonation process and the resulting acoustic quality.