I dunno how the tech actually works, but sound is something I do know!

[Jet pilots were rather intimate with the sound barrier after all.]

See, sound is basically vibrations going through the air in waves. That's how these phone devices work, they detect the vibrations in the air, and then replicate it on the other end.

Apparently Lucio's gear uses unique vibrations that our ears pick up on, and cause a chain reaction through the body to help it heal injuries faster. Dunno how, but it's a real life saver.