Simulation of Losses Due to Turbulence in the Time-Varying Vocal System

Flow separation in the vocal system at the outlet of a constriction causes turbulence and a fluid dynamic pressure loss. In articulatory synthesizers, the pressure drop associated with such a loss is usually assumed to be concentrated at one specific position near the constriction and is represented by a lumped nonlinear resistance to the flow. This paper highlights discontinuity problems of this simplified loss treatment when the constriction location changes during dynamic articulation. The discontinuities can manifest as undesirable acoustic artifacts in the synthetic speech signal that need to be avoided for high-quality articulatory synthesis. We present a solution to this problem based on a more realistic distributed consideration of fluid dynamic pressure changes. The proposed method was implemented in an articulatory synthesizer where it proved to prevent any acoustic artifacts