3D geometry of the vocal tract and inter-speaker variability

Three speakers of French (two males and one female) were the subjects of an MRI analysis of the vocal tract during the production of sustained isolated French vowels. From a 3D reconstruction of the vocal tract, area functions were determined for each vowel, and the corresponding formant values were computed with a harmonic model of the vocal tract. Using the computation of the sensitivities of the formants to area function changes, the main affiliations between formants and cavities were found, and a resonance based approach was used to predict the acoustical inter-speaker variability. Comparing these predictions with the actual differences measured between speakers, together with observations of the area functions, show the limits of the method if the patterns of affiliation and the nature of the resonances are different from one speaker to another. 1