Stereoscopic Particle Image Velocimetry Measurement of Articulatory Airflow for Validation of a Computer Model of Speech

Abstract

The interaction of the airflow and the vocal articulators while speaking is not completely understood. The regions of articulation in the airway are flow obstructions that convert aerodynamic energy into acoustic energy and can be passive (stationary) such as the teeth and hard palette, or active (moving) in the case of the lower lip and tongue. By modifying the positions of the vocal articulators and the various sounds that make up speech can be generated. Models of the articulators have been constructed from Magnetic Resonance Imaging (MRI) scans taken during quiet breathing, and articulatory kinematics were obtained from Electromagnetic Articulography (EMA) and a video of the face. A three-dimensional computer model that can represent the motion of vocal articulators and simulate the airflow during vowels and consonants has also been developed. A fricative is a hissing or buzzing consonant that is produced when a steady air stream is forced through a constriction in the oral cavity and the flow state becomes transitional or even turbulent. In the current paper Stereoscopic Particle Image Velocimetry (SPIV) measurements of the airflow through the modelled vocal tract geometries for the production of "s" and "sh" fricatives are presented.