Best paper and presentation award in Forum Acusticum 2014 to an acoustic researcher in La Salle R&D
The acoustics area from La Salle R&D was present in the Forum Acusticum 2014, held in Krakow (Poland), from the 7th to the 12th of September. The researchers Marc Arnela and Dr. Oriol Guasch from the acoustics area attended this international conference on acoustics.
Marc Arnela presented two works framed within the European EUNISON project. The first one entitled “three-dimensional behavior in the numerical generation of vowels using tuned two-dimensional vocal tracts”, coauthored with Dr. Oriol Guasch, and the second one on “Finite element computation of diphthong sounds using tuned two-dimensional vocal tracts”, coauthored with Dr. Oriol Guasch, and Dr. Ramon Codina and Héctor Espinoza from the centre for numerical methods CIMNE in Barcelona.
Marc Arnela was awarded the “Best Paper and Presentation Award for young researchers” by the European Acoustics Association (EAA).
One-dimensional (1D) methods for vowel production modelling suffer from several well-known limitations, whereas full three dimensional (3D) numerical simulations still result in very high computational costs. In this context, two-dimensional (2D) approaches may provide a good balance between voice quality and computational demands. However, most existent 2D vocal tract models are given the same radius function, wall impedance and glottal flow used in 3D models, which induce significant errors in the generated sound. In this work, it is proposed to perform some simple modifications on 2D vocal tracts, so that 2D simulations can match the formant locations, bandwidths and amplitudes of 3D vocal tracts with circular cross-section. The procedure is exemplified on vowels /a/, /i/ and /u/, and the results compared to standard 1D, 2D and 3D approaches. Numerical simulations are carried out using the finite element method.
Finite element methods (FEM) are increasingly being used to simulate the acoustics of the vocal tract. For vowel production, the irreducible wave equation for the acoustic pressure is typically solved. However, diphthong sounds require moving vocal tract geometries so that the wave equation has to be expressed in an Arbitrary Lagrangian-Eulerian (ALE) framework. It then becomes more convenient to directly work with the wave equation in its mixed form, which not only involves the acoustic pressure but also the acoustic velocity. In turn, this entails some numerical difficulties that require resorting to stabilized FEM approaches. In this work, FEM simulations for the wave equation in mixed form are carried out to produce some diphthongs. Tuned two-dimensional vocal tracts are used which mimic the behavior of three-dimensional vocal tracts with circular cross-section.