UNIFORM AND NONUNIFORM NORMALIZATION OF VOCAL TRACTS MEASURED BY MRI ACROSS MALE, FEMALE AND CHILD SUBJECTS

Three-dimensional vocal tract shapes of a male, a female and a child s ubjects are measured from magnetic resonance (MR) images during sustai ned phonation of Japanese vowels /a, i, u, e, o/. Non-uniform dimensio nal differences in the vocal tract shapes of the subjects are quantita tively measured. Vocal tract area functions of the female and child su bjects are normalized to those of the male on the basis of non-uniform and uniform scalings of the vocal tract length and compared with each other. A comparison is also made between the formant frequencies comp uted from the area functions normalized by the two different scalings. It is suggested by the comparisons that non-uniformity in the vocal t ract dimensions is not essential in the normalization of the five Japa nese vowels.