Pitch Accent Trajectories across Different Conditions of Visibility and Information Structure - Evidence from Spontaneous Dyadic Interaction

Previous research identified a differential contribution of information structure and the visibility of facial and contextual information to the acoustic-prosodic expression of pitch accents. However, it is unclear whether pitch accent shapes are affected by these conditions as well. To investigate whether varying context cues have a differentiated impact on pitch accent trajectories produced in conversational interaction, we modified the visibility conditions in a spontaneous dyadic interaction task, i.e. a verbalized version of TicTacToe. Besides varying visibility, the game task allows for measuring the impact of information-structure on pitch accent trajectories, differentiating important and unpredictable game moves. Using GAMMs on four speaker groups (identified by a cluster analysis), we could isolate varying strategies of prosodic adaptation to contextual change. While few speaker groups showed a reaction to the availability of visible context cues (facial prosody or executed game moves), all groups differentiated the verbalization of unpredictable and predictable game moves with a group-specific trajectory adaptation. The importance of game moves resulted in differentiated adaptations in two out of four speaker groups. The detected strategic trajectory adaptations were characterized by different characteristics of boundary tones, adaptations of the global f0-level, or the shape of the corresponding pitch accent.