A comparison between vocal tract length estimates from acoustic and x-ray data

Abstract

Thirty vocal tract length measurements from lip corners to glottis were obtained from cine-x-ray sagittal views and lateral-frontal photographic data. Material for two French speakers includes vowels [i, ɛ, ɑ, ɔ, u] in three symmetric [ə CVC] frames where C is either [b, d] or [g]. Four formant frequencies were measured from the simultaneous audio recording using covariance LPC on closed glottis sections, and were corrected for the frequency effects of lip radiation and wall vibrations. Calculated bandwidths from Fant's data and the modified formant frequencies were used to derive area functions for several tract lengths. Use of Paige and Zue's criterion [IEEE-AU 18, 268–270 (1970)] of minimum perturbation with respect to a uniform tube yielded close agreement between measured and estimated lengths for all vowels except [u]. Removal of the last (lip) section in criterion calculations gives better results for [u].