Piecewise-planar representation of vowel formant frequencies across speakers
David J. Broad · The Journal of the Acoustical Society of America · 1978
A previous study [J. Acoust. Soc. Am. 62, 1467–1473 (1977)] showing that a single female speaker's first three vowel formant frequencies clustered about a two-part piecewise-planar surface is extended to five additional speakers. For each speaker, a similar two-plane representation is found, with the rms spread of the data about the planes being about the same for all speakers. Also, the orientations of the planes for the different speakers are similar: for the data collected so far, the back-vowel planes make an rms angle of about 10° to the average back-vowel plane, while the front vowels make about a 15° rms angle to the average front-vowel plane, Though relatively small, these variations in orientation are significant at the 99% level. As a consequence, the hypothesis of uniform scaling of vowel formant frequencies between speakers must be rejected if it is carried strictly to three dimensions. [This work supported by the AFOSR (AFSC) under Contract F44620-74-C-0034.]