Perception of anticipatory coarticulation effects.

Abstract

Articulatory and acoustic studies have shown that the effects of anticipatory coarticulation may extend across several segments in an utterance. But previous perceptual studies suggest that only the information carried by immediately adjacent segments is used in perception. To show that perception is not so limited, we persuaded ten talkers each to produce 12 sentences (e.g., "I say poozee") of the form "I say /C V1 z V2/" in which C was /p, t, k/, V1 was /u, ae/, and V2 was /i, a/. Each /i, a/ sentence pair was cross spliced by exchanging the final syllable /z V2/ so that coarticulatory information prior to the crosspoint was inappropriate for the final vowel V2 in crossed sentences. Recognition time (RT) for V2 in crossed and intact (as spoken) sentences was obtained from practiced listeners. The results were slower RT in crossed sentences, and amount of interference depended on both V1 and C context. Another experiment varied the location of crosspoints across /C V1/ and found that RT interference increased directly with amount and proximity to target of inappropriate precross acoustics. LPC analysis of the experimental sentences showed pretarget variations in F2 frequency which were jointly dependent on identity of C, V1, and V2. Pretarget F2 variations and C and V1 identity jointly predicted amount of RT interference in crossed sentences. Finally, experiments with pretarget F2 variations in synthetic speech repeated and extended the results with real speech. These studies lead to the conclusion that the perceptual significance of coarticulation is not limited to effects on immediately adjacent segments. Listeners appear to be sensitive to many acoustic effects of the mutual influence among the segments in a sequence.