Within-Word Prosodic Constraint on Coarticulation in Japanese

The present study addresses the question of how within-word prosodic constituent boundaries constrain V-to-V coarticulation in Japanese. The smallest prosodic unit that might affect V-to-V coarticulation is the bimoraic foot. The effect of the foot boundary is observed in the present study: the bimoraic foot constrains the extent of V-to-V coarticulation in both left-to-right and right-to-left directions. For the target vowel /a/, anticipatory V-to-V effects are stronger than carryover effects for both within-foot and across-foot conditions. Also, the foot constraint works more strongly on anticipatory than on carryover effects. Some idiosyncratic variation is observed across speakers; however, even some deviant behavior can partly be explained as the result of the interaction of C-to-V and V-to-V effects and speech rate. Coarticulation is observed to be the product of a complex process of constraint interaction.