Prosodic Facilitation and Interference While Judging on the Veracity of Synthesized Statements

Two primary sources of information are provided in human speech. On the one hand, the verbal channel encodes linguistic content, while on the other hand, the vocal channel transmits paralinguistic information, mainly through prosody. In line with several studies that induce a conflict between these two channels to better understand the role of prosody, we conducted an experiment in which subjects had to listen to a series of statements synthesized with varying prosody and indicate if they believed them to be true or false. We find evidence suggesting that acoustic/prosodic (a/p) features of the synthesized statements affect response times (a well-known proxy for cognitive load). Our results suggest that prosody in synthesized speech may play a role of either facilitation or interference when subjects judge the truthfulness of a statement. Furthermore, we find that this pattern is amplified when the a/p features of the synthesized statements are analyzed relative to the subjects’ own a/p features. This suggests that the entrainment of TTS voices has serious implications in the perceived trustworthiness of the system’s skills.