Generating vocal tract shapes from formant frequencies

An algorithm that uses only the first three formant frequencies has been devised for generating vocal tract shapes as seen on midsagittal x-ray diagrams of most English vowels. The shape of the tongue is characterized in terms of the sum of two factors derived from PARAFAC analysis: a front raising component and a back raising component. Stepwise multiple regression techniques were used to show that the proportions of these two components, and of a third parameter corresponding to the distance between the lips, are highly correlated with the formant frequencies in 50 vowels. The recovery algorithm developed from these correlations was tested on a number of published sets of tracings from x-ray diagrams, and appears to be generalizable to other speakers.