William A. Ainsworth
Dept. of Commun. and Neurosci., Keele Univ., Keele, Staffordshire ST5 5BG, United Kingdom
Second-formant transitions in vowel--vowel utterances are not always of the same duration as those of the first formant and they often begin and end at different instants. In other cases the formant frequencies sometimes first move in a different direction from their final targets. In order to investigate whether these formant movements are perceptually significant, a number of difference limens for formant transitions have been measured for synthesized versions of the vowel pair /a/--/i/. It was found that differences in duration between the first- and second-formant transitions of up to 70 ms were not perceived. It was also found that delays between the starts and ends of the first and second transitions of up to 50 ms were not perceived. These results suggest that the differences in durations and delays between the first and second formants found in natural vowel--vowel utterances are unlikely to be of perceptual significance. [Work supported by EC Science Contract SC1-CT92-0786.]