Prosodic strengthening in transboundary V-to-V lingual movement in American English.

This study investigates how prosodic strengthening is kinematically manifested in V-to-V lingual movement in English CV#CV context (where # is a prosodic boundary). Results showed that both boundary and accent gave rise to a kind of prosodic strengthening (showing spatial and temporal expansion), but exact kinematic patterns of prosodic strengthening were different as a function of the type of gesture (tongue lowering versus raising) associated with different vowels (/i/to-/ alpha/ vs. /alpha/-to-/i/) and the source of prosodic strengthening (boundary versus accentuation). This implies that speakers must know about prosodic structure and differentiate the two sources of prosodic strengthening in a systematic fine-grained fashion. From a theoretical point of view regarding a mass-spring gestural model, results suggested that kinematic patterns of prosodic strengthening could not be fully accounted for by any particular dynamical parameter, presenting a complex nature of prosodic strengthening. The results also implied that the theory of the pi-gesture (the prosodic boundary gesture) under the rubric of the mass-spring gestural model needs to be refined in terms of how the theory defines the exact scope of the pi-gesture's influence in the temporal dimension and how it differentiates boundary-induced articulation from an accent-induced one.