When aiming to design for intuitive interaction, a good understanding of hu- man behavior is essential. In this chapter we dive into studies on how humans use vocalizations and prosody in everyday interaction. Contrasting six ex- amples from human-human and human-robot interaction, we highlight how insights on human practices can inform the design of robot sound in interac- tion. We present three main lessons, demonstrating that a) both human vo- calizations and robot sound are semantically underspecified, b) human sound production is embodied, and robot sound should therefore be analyzed and designed multimodally, and c) sound can be easily adapted for complex par- ticipation.