Influence of a realistic human head on the directivity of vowel /a/ based on three-dimensional finite element simulations

Abstract

The human voice can be accurately simulated using three-dimensional (3D) finite element simulations. These simulations involve the generation of sound waves from the vocal cords, their 3D propagation through a detailed 3D vocal tract, usually generated from Magnetic Resonance Imaging (MRI), and their emission outward from the lips. Most studies have focused on internal aspects of the vocal tract, which allowed them to simplify the human head as a spherical baffle or a flat plane. However, it is not clear to what extent this simplification affects the directivity of the voice. This work aims at examining 3D directivity effects of vowel sounds in the horizontal and vertical planes by means of finite element simulations. A detailed geometry is generated for this purpose, consisting of a 3D MRI-based vocal tract connected to a realistic human head designed from scratch. Preliminary results are presented for the vowel /a/, showing that large variations occur in the vocal tract acoustic response as the orientation and frequency increases for both the horizontal and vertical planes. These variations are especially notorious above 5 kHz, since in this frequency range not only planar modes but also higher order modes propagate through the vocal tract.