PERCEPTION OF SYNTHETIC 2-FORMANT VOWEL TRANSITIONS

Speech analysis shows that the second formant transitions in vowel-vow el utterances are not always of the same duration as those of the firs t formant transitions nor are they always synchronised. Moreover the f ormant transitions often move initially in a different direction from their final target. In order to investigate whether these deviations f rom linearity and synchrony are perceptually significant a series of l istening tests have been conducted with the vowel pair /a/-/i/. It was found that delays between the first and second formant transitions of up to 30 ms are not perceived, nor are differences in duration of up to 40 ms if the first and second formants start or end simultaneously. If the second formant transition is symmetric in time with respect to the first formant differences of up to 50 ms are tolerated. Excursion s in second formant transition shape of up to about 500 Hz are also no t perceived. These results suggest that most of the deviations from li nearity and synchrony found in natural vowel-vowel utterances are not perceptually significant.