While the lexico-grammatical and embodied practices in various instructional activities have been explored in-depth (Keevallik, 2013; Simone & Galatolo, 2020), the vocal capacities deployed by instructors have not been in focus. This study looks at how a Pilates instructor coaches student bodies by modulating the prosodic production of verbal instructions and adjusting vocal quality in reflexive coordination with the students ongoing movements. We show how the body of one participant can be expressed and enhanced by anothers voice in a simultaneous assembly of action and argue for the dialogical conceptualization of a speaker. These voice-body assemblies constitute evidence of how actions were brought about jointly rather than constructed individually.