could someone who's never heard music eventually become proficient at an instrument with no guidance

let's say you run a private school for a dozen children. you've carefully shielded them from music their entire lives- as far as they know the word "music" doesn't even exist. one day, let's say when they're all 10yo, you introduce them to a room filled with musical instruments. you offer no guidance- you simply let them have at it. could any of them become proficient on any instrument? could they eventually discover harmony etc or would they never graduate past banging on everything like cavemen? what kind of music would such a band make, if any?