Social effects on vocal rate with echoic mimicry using prosody-only voice

We have been studying some of the essential factors that constitute interpersonal relations between humans and computers by focusing on social bonding in proto-communications (the interaction between adults and human infants or pets). From this viewpoint, this paper presents psychological experiments on the interaction between humans and animated characters that mimic the human voice at the prosodic level using prosodyonly voice under different vocal rate of character’s voice: (a) faster than normal, (b) normal speed, and (c) slower than normal. We examine the subjects’ impression towards animated characters with the above conditions of their voice using postquestionnaire and analyse the change of the speech rate of subjects. The results indicate that most humans may prefer an animated character with a faster voice to that with a slower voice. Moreover, the speech rate of humans changes to opposite of vocal rate of animated characters’ voice. I.e. the speech rate of subjects becomes slower when the voice of character becomes faster, and vice versa.