Vocal tract area functions of 13 Swedish vowels have been derived from midsagittal tracings of X-ray pictures, supported by a limited tomographic material. With a few exceptions, e.g. F2 of [u:], [o] and [o], calculated formant frequencies show a substantial agreement with data measured during the X-ray session. The sensitivity of formant frequencies to variations in vocal tract area functions have been studied.

Observed covariation of overall vocal tract dimensions revealed a number of dependent relationships that enable a prediction of overall length, inter-incisor distance, and assymmetries of cavity shapes from the basic specification of location and area of tongue constriction and the degree of liprounding. The new model thus preserves physiological constraints that make it better suited for a future adaption to consonantal modifications than earlier three-parameter models. Nomograms of formant frequencies for systematically varied model parameters are shown. Problems related to inverse mapping, from formant frequencies to model parameters, are discussed.