The Impression of Phones and Prosody Choice in the Gibberish Speech of the Virtual Embodied Conversational Agent Kotaro

Abstract

The number of smart devices is expected to exceed 100 billion by 2050, and many will feature conversational user interfaces. Thus, methods for generating appropriate prosody for the responses of embodied conversational agents will be very important. This paper presents the results of the “Talk to Kotaro” experiment, which was conducted to better understand how people from different cultural backgrounds react when listening to prosody and phone choices for the IPA symbol-based gibberish speech of the virtual embodied conversational agent Kotaro. It also presents an analysis of the responses to a post-experiment Likert scale questionnaire and the emotions estimated from the participants’ facial expressions, which allowed one to obtain a phone embedding matrix and to conclude that there is no common cross-cultural baseline impression regarding different prosody parameters and that similarly sounding phones are not close in the embedding space. Finally, it also provides the obtained data in a fully anonymous data set.

Keywords

• embodied conversational agents
• synthetic gibberish speech
• prosody generation