Personalized Synthesis of Intentional and Emotional Non-Verbal Sounds for Social Robots

Non-verbal sounds are an essential communication channel for social robots. However, it requires expert knowledge to create and compose synthesizers, develop melodic structures or record samples which express a robot's internal intentions and emotions. This paper presents an approach for adapting a robot's timbre based on non-expert human comparative feedback in order to personalize the sonic interaction design to an individual user's preferences. An evolution strategy learns parameters of real-time sound synthesis for different intentions and emotions. Ultimately, the strategy aims to improve the perceived goodness of how well a specific melody's sound maps to a specific emotion or intention. In order to demonstrate the feasibility of the approach, we report on a user study with a robot, 6 exemplary melodies and 27 participants. Our study results show that the strategy indeed results in improved and preferred sound designs and that many participants are willing to apply such a process to improve their robots' expressivity.