Which Voice for which Robot? Designing Robot Voices that Indicate Robot Size

Many social robots will have the capacity to interact via speech in the future, and thus they will have to have a voice. However, so far it is unclear how we can create voices that fit their robotic speakers. In this paper, we explore how robot voices can be designed to fit the size of the respective robot. We therefore investigate the acoustic correlates of human voices and body size. In Study I, we analyzed 163 speech samples in connection with their speakers’ body size and body height. Our results show that specific acoustic parameters are significantly associated with body height, and to a lesser degree to body weight, but that different features are relevant for female and male voices. In Study II, we tested then for female and male voices to what extent the acoustic features identified can be used to create voices that are reliably associated with the size of robots. The results show that the acoustic features identified provide reliable clues to whether a large or a small robot is speaking.