The Vocal Tract Geometry ( Mri ) Essay

967 Words Sep 8th, 2016 4 Pages
The vocal tract geometry has a very complex three-dimensional (3D) shape. Its volume representation has been captured in many works by using, for instance, magnetic resonance imaging (MRI) (see, e.g., Rokkaku et al., 1986; Baer et al., 1991; Story et al., 1996; Engwall and Badin, 1999) or computed tomography (CT) (see, e.g., Sundberg et al., 1987). For years, this volume has subsequently been simplified to generate a vocal tract area function, which describes the variations of the cross-sectional area along its center midline. This has allowed 1D approaches to generate voice with a fairly good quality and also with a large flexibility thanks to the low dimensional representation of the vocal tract geometry (see, e.g., Kelly and Lochbaum, 1962; Fant, 1970; Sondhi and Schroeter, 1987; Story, 2005; Doel and Ascher, 2008; Story, 2013; Birkholz, 2013). However, it is well known that this classical approach can only approximate vocal tract acoustics in the low frequency range (below 4–5 kHz) where the plane wave assumption is satisfied. For higher frequencies, higher order modes are also excited (see, e.g., Blandin et al., 2015) that cannot be captured by 1D methods. Beyond this, little is known on the information that is lost when simplifying the complex 3D vocal geometry to a 1D area function. It is the main purpose of this work to shed some light on this topic.
Current 3D approaches have allowed one to directly resort to 3D vocal tract geometries and deal with the induced…

Related Documents