Finite element simulation of /asa/ in a three-dimensional vocal tract using a simplified aeroacoustic source model

The numerical simulation of fricative sounds in three-dimensional (3D) vocal tracts typically involves hybrid Computational Aeroacoustics (CAA) approaches. Unfortunately, those are very costly and require from supercomputer facilities to produce a mere few milliseconds of sound. The problem becomes prohibitive if one not only aims at generating a single fricative, but also sequences containing both, vowels and fricatives. It then seems wise to try to approximate somehow the flow noise sources, so that only an acoustic simulation becomes necessary. That avoids the very demanding computational fluid dynamics step in CAA. Aeroacoustic sources can be modeled to different levels of precision. In this work, it is suggested to follow a similar methodology to that in one-dimensional (1D) techniques, but applied to 3D dynamic vocal tracts. Vowel sounds are produced introducing glottal pulses at the vocal tract entrance (glottis), while monopole and dipole sources consisting of white noise are activated in the region where a fricative sound is generated. Acoustic wave propagation in a 3D dynamic vocal tract is simulated using a stabilized Finite Element Method (FEM) for the wave equation in mixed form, set in an Arbitrary Lagrangian-Eulerian (ALE) framework. The sequence /AsA/ is produced as an example.