Some current challenges in unified numerical simulations of voice production : from biomechanics to the emitted sound

Voice production all the way from muscle activation to sound - are we there yet? Three-dimensional (3D) numerical simulations of the entire process of voice generation appear to be very challenging. Muscle activations position the articulators, which define a vocal tract geometry and posture the vocal folds. Air emanating from the lungs induces self-oscillations of the vocal folds, which result in aeroacoustic sources and the subsequent propagation of acoustic waves inside the vocal tract (VT). There, many things could happen. For instance, the air could resonate to generate vowels, or, at constrictions, airflow may be accelerated to create turbulent sounds such as fricatives. The vocal tract walls are flexible and react to the inner acoustic pressure. Also, articulators can change the vocal tract geometry to generate vowel-vowel utterances or syllables. Sound is finally radiated from the mouth.Attempting unified 3D numerical simulations of all the above processes, which involve coupling of a biomechanical model and the mechanical, fluid and acoustic fields, may seem unwise. Most research to date has addressed a few selected aspects of voice production. Unified approaches have been shunned for their daunting complexity and high-performance parallel computation requirements. This situation now seems to be changing. In this paper, we briefly review recent approaches towards 3D realistic voice simulation that unify, at least to some extent, some of the involved physical fields. Remaining challenges will be highlighted. We will focus on those works which end with the production of a given sound, thus leaving aside the huge amount of literature solely devoted to the complex simulation of phonation.QC 20180112FET-Open 308874 Euniso