Persuasive Synthetic Speech: Voice Perception and User Behaviour

Previous research indicates that synthetic speech can be as persuasive as human speech. However, there is a lack of empirical validation on interactive goal-oriented tasks. In our two-stage study (online listening test and lab evaluation), we compared participants' perception of the persuasiveness of synthetic voices created from speech in a debating style vs. speech from audio-books. Participants interacted with our Conversational Agent (CA) to complete 4 flight-booking tasks and were asked to evaluate the voice, message and perceived personal qualities. We found that participants who interacted with the CA using the voice created from debating style speech rated it as significantly more truthful and more involved than the CA using the audio-book-based voice. However, there was no difference in how frequently each group followed the CA's recommendations. We hope our investigation will provoke discussion about the impact of different synthetic voices on users' perceptions of CAs in goal-oriented tasks.