Attempts by human speakers to reproduce Fant's nomograms

Abstract

Fant's nomograms, which constitute a simulation of the acoustic resonances which result from different vocal tract shapes, were checked against natural vowels by two phoneticians carefully producing a full range of vowel articulation in which (a) the location of the minimum aperture in the vocal tract and (b) the lip aperture were separately varied. Spectrographic measurements of formant frequencies were made, some with synchronised lip photographs. Ultrasonic and radiographic methods were used to verify vocal tract constriction size. In many major respects our data agreed with Fant's predictions, but three main kinds of discrepancies were noted: firstly, we could not produce as great a range of variations as occurs in the nomograms; secondly, when an [i]-like constriction is moved as far forward as possible, the frequency of F2 does not decrease; and thirdly, variations in lip rounding affect high front vowels and high back vowels differently with no gradual change from one class to the other as in Fant's data.