Abstract:

Self-sustained oscillation of the vocal folds was simulated by combining two-dimensional laryngeal airflow with multidimensional tissue movement. A finite-element model was used for the solution of viscoelastic waves in the tissue and a finite-volume method was used in the solution of Navier--Stokes equations for the airflow. A so-called ``shadow method'' simulated the glottal constriction in the flow model to avoid the complexity of grid movement. The two-dimensional flow equations were solved in an iterative manner until the given transglottal pressure was approximated. The flow solution was then used in the estimation of the aerodynamic forces on the tissue, required in the finite-element solution of tissue movement. The results indicate that inlet velocity profiles to the glottis are almost parabolic at any instant of time. The glottal velocity increases to its maximum at the glottal exit at the center of a jet, with values exceeding 40 m/s for 0.8 kPa of lung pressure. The jet velocity waveform is similar to that of an excised larynx and the pressure profiles are similar to those of steady flows in physical models. Also, the displacement of the inferior portion of the vocal folds leads the superior position in phase.