Analysis of aeroacoustic sources in a hybrid simulation of human phonation using perturbed convective wave equation

The sources of human voice production are investigated based on a validated voice model. This analysis is performed using a hybrid aeroacoustic workflow: 3D incompressible, turbulent flow simulation using STARCCM+, source term computation and interpolation, and 3D acoustic wave propagation simulation based on the perturbed convective wave equation using openCFS. During the detailed effect analysis, the far-field sound spectra are compared quantitatively, and the flow-induced sound sources are visualized within the larynx. The source visualization shows that if the vocal folds (VFs) are not  fully closing (as it is the case for several types of voice disorders), the VFs motion provides reduced source energy to the flow-induced sound and the source energy during one cycle is not cut-off entirely. Therefore, turbulent and vortical structures are permanently present increasing the broadband component of the voice signal. Furthermore, comparison of the source field in time- and frequency-domain shows that although the convective part of the source dominates a source visualization locally near the vocal folds, it is negligible in its contribution to the radiated sound. Neglecting the convective part of the source term reduces the validation error by only 0.6 % in the far field in comparison to the full formulation.