On Pushing the Voice-Onset-Time (Vot) Boundary About

There is voluminous evidence that homorganic stop consonants are distinguishable on the basis of voice onset time relative to their supraglottal articulation. For initial stops a convenient acoustic reference point is the onset of the release burst, and VOT has been defined as the interval between this point and onset of glottal signal. VOT boundary values between voiced and voiceless initial stops of English have been established by spectrographic measurements of naturally produced isolated words and by perception testing of synthesized CV syllables. The close match between the two kinds of boundary values suggests that fairly natural values were chosen for the invariant features of the synthetic speech patterns tested. It is known, however, that certain of these affect voicing perception. New data from synthesis experiments show that VOT boundaries shift with changes in transition duration, and that it is the first formant and not higher ones which are responsible.