The effect of stress on F2 onsets in VCV utterances

Abstract

This study compares a superposition or vowel-to-vowel theoretical framework versus a segment-by-segment account to best account for the coarticulatory dynamics of VCV utterences. The ‘‘trough effect,’’ a deactivation of tongue musculature after the initial vowel of a symmetrical VCV sequence (e.g., /ibi/), is not readily explainable by traditional co-production (vowel-to-vowel) accounts of coarticulation. A Jossian segment-by-segment programming sequence appears to be more compatible with ‘‘deactivation’’ phenomena. One way to manipulate extent of ‘‘deactivation’’ is to impose differential degrees of syllable stress on either side of the stop consonant. Locus equations can provide an acoustic window on this question as timing differences should show up as slope/intercept variations. Emphatic stress on V1 is expected to lessen deactivation relative to weak V1 stress, and consequently greater levels of anticipatory coarticulation should occur, resulting in higher locus equation slopes. Four different stress-vowel conditions were used: weak versus emphatic stress counterbalanced over V1 and V2. There were five vowel contexts for V1 and ten vowel contexts for V2, surrounding the three voiced stop consonants /b, d, g/. Results will be reported on three speakers of American English. [Work supported by NIH.]