An audio/visual system (e.g., such as an entertainment console or other computing device) plays a base audio track, such as a portion of a pre-recorded song or notes from one or more instruments. Using a depth camera or other sensor, the system automatically detects that a user (or a portion of the user) enters a first collision volume of a plurality of collision volumes. Each collision volume of the plurality of collision volumes is associated with a different audio stem. In one example, an audio stem is a sound from a subset of instruments playing a song, a portion of a vocal track for a song, or notes from one or more instruments. In response to automatically detecting that the user (or a portion of the user) entered the first collision volume, the appropriate audio stem associated with the first collision volume is added to the base audio track or removed from the base audio track.