Emotional musical prosody for the enhancement of trust: Audio design for robotic arm communication

Abstract As robotic arms become prevalent in industry, it is crucial to improve levels of trust from human collaborators. Low levels of trust in human–robot interaction can reduce overall performance and prevent full robot utilization. We investigated the potential benefits of using emotional musical prosody (EMP) to allow the robot to respond emotionally to the user’s actions. We define EMP as musical phrases inspired by speech-based prosody used to display emotion. We tested participants’ responses to interacting with a virtual robot arm and a virtual humanoid that acted as a decision agent, helping participants select the next number in a sequence. We compared results from three versions of the application in a between-group experiment, where the robot presented different emotional reactions to the user’s input depending on whether the user agreed with the robot and whether the user’s choice was correct. One version used EMP audio phrases selected from our dataset of singer improvisations, the second version used audio consisting of a single pitch randomly assigned to each emotion, and the final version used no audio, only gestures. In each version, the robot reacted with emotional gestures. Participants completed a trust survey following the interaction, and we found that the reported trust ratings of the EMP group were significantly higher than both the single-pitch and no audio groups for the robotic arm. We found that our audio system made no significant difference in any metric when used on a humanoid robot implying audio needs to be separately designed for each platform.