Vocal tract shapes and area functions from magnetic resonance imaging (MRI)

Abstract

There have been considerable research efforts in acoustic modeling of speech but there is still only a small body of information regarding direct three-dimensional measurements of the vocal tract shape. The purpose of this study was to acquire, using MRI, an inventory of three-dimensional vocal tract airway shapes that correspond to a particular set of vowels and consonants. The MR imaging was carried out for one subject (29-yr-old male, native of the midwestern United States) using a GE Signa 1.5-T scanner. The images were reconstructed and analyzed with a general display and quantitation package. The resulting three-dimensional (3D) vocal tract shapes were analyzed to find the cross-sectional areas perpendicular to the centerline extending from the glottis to the mouth to produce an ‘‘area function.’’ These area functions were then used as input to a wave-reflection type model of one-dimensional acoustic-wave propagation in the vocal tract. 3D reconstructions and area functions of the vocal tract shapes will be shown and the corresponding simulations of the speech sounds will be demonstrated.