Analytical and Numerical Modeling of Vocal Tract in Vowel Phonation

Álvaro Campos Ferreira¹; Marcus Vinicius Girão de Morais¹

¹ Universidade de Brasília

doi:10.20906/CPS/CILAMCE2015-0466

Resumo

The acoustical properties of the vocal tract have been the subject of several studies due to the complex nature of the human voice. The complex geometry the vocal tract assumes during the phonation of vowels is obtained from Magnetic Resonance Imaging (MRI) and acoustic models are constructed to determine the resonance frequencies, also known as formants, which characterizes the sound of the vowel. This information can be used by health professionals to identify possible voice pathologies. The objective of this work is to model the acoustic behavior of a vocal tract using an analytical and a numerical method, namely, the transfer matrix method and the boundary elements method. This work presents the acoustic behavior of both a simplified model of a vocal tract and a model with complex geometry based on the experimental measurements of a vocal tract during the phonation of vowels. Analytical and numerical models are used to predict the acoustic behavior of the vocal tract geometry. We provide two models: a transfer matrix analytical solution and a boundary elements modeling. The implementation are carried out in MATLAB. This paper presents resonance frequencies and respective mode shapes. Both models have shown good agreement for distinct resonance frequencies and related mode shapes. A comparison between the mode shapes for each resonance frequency is carried out to guarantee that the same mode shapes are being compared in both methods. The analytical and numerical models have shown good agreement both when compared between themselves and between the results from the bibliography. The mode shapes produced by the present work are consistent with the acoustic behavior of open-closed cavities.

Palavras-chave: modal analysis; vocal tract; boundary element method; transfer matrix method; acoustics