A comparative study of two-dimensional vocal tract acoustic modeling based on Finite-Difference Time-Domain methods

TL;DR

This paper compares a new 2.5D FDTD vocal tract acoustic model with existing 2D FDTD and 3D FEM models, demonstrating comparable accuracy at lower resolutions and analyzing radiation effects across vowel shapes.

Contribution

Introduces and evaluates a novel 2.5D FDTD vocal tract model that balances computational efficiency and accuracy, extending previous 2D approaches with added depth.

Findings

The 2.5D FDTD model produces acoustic outputs comparable to 2D FDTD and 3D FEM models at low resolution.

Inclusion of a circular baffle enables analysis of radiation transfer functions for different vowels.

The model effectively captures vowel-specific acoustic characteristics with reduced computational cost.

Abstract

The two-dimensional (2D) numerical approaches for vocal tract (VT) modelling can afford a better balance between the low computational cost and accurate rendering of acoustic wave propagation. However, they require a high spatio-temporal resolution in the numerical scheme for a precise estimation of acoustic formants at the simulation run-time expense. We have recently proposed a new VT acoustic modelling technique, known as the 2.5D Finite-Difference Time-Domain (2.5D FDTD), which extends the existing 2D FDTD approach by adding tube depth to its acoustic wave solver. In this work, first, the simulated acoustic outputs of our new model are shown to be comparable with the 2D FDTD and a realistic 3D FEM VT model at a low spatio-temporal resolution. Next, a radiation model is developed by including a circular baffle around the VT as head geometry. The transfer functions of the radiation model are analyzed using five different vocal tract shapes for vowel sounds /a/, /e/, /i/, /o/ and /u/.