The Sousaphone is a musical instrument included in the RUST Instruments Pack DLC, which must be purchased from the Steam store.
You can play the sousaphone by pressing Mouse One and Mouse Two. You can also press the R key to turn your keyboard into an array of instrumental notes.
Alternatively, you can hook up a midi-player to play your favorite songs, or you can load midi’s into your RUST folder and play them using the RUST console command line. Check out our RUST instruments guide for a deeper dive into instrument setup.
If you want to turn off RUST instrument sounds, you can turn them off in the settings without affecting other game sounds.