Vowel perception: Spectral shape versus formants

Abstract

Traditional theories of vowel perception favor formants over global spectral shape as the primary perceptual cues to vowel identity. In previous ASA meetings, results of speaker-independent automatic recognition experiments for vowels were reported that contrasted global spectral shape versus formants [A. J. Jagharghi and S. A. Zahorian, J. Acoust. Soc. Am. Suppl. 1 81, S18 (1987); S. A. Zahorian and A. J. Jagharghi, J. Acoust. Soc. Am. Suppl. 1 82, S37 (1987)]. These results indicate that automatic recognition rates based on global spectral shape are generally slightly superior to recognition rates based on formants. In the present study, the perception of vowels is investigated for vowels synthesized such that the synthesized tokens contain conflicting cues to vowel identity based on overall spectral shape versus formants. Two distinct but close vowels are selected. The spectral shape of the first vowel is modified to match, to the extent possible, the spectral shape of the second vowel without any change in the formant frequencies for F1, F2, and F3. Thus the modified vowel has the same formants as the first vowel, but its spectral shape matches that of the second vowel. Listening experiments indicate that, for most conditions, the modified vowel segments are perceived according to spectral shape cues rather than formant cues. The details of the experimental procedures and the results of the listening experiments will be presented at the meeting. [Work supported by NSF.]