This all happened years ago. As a child, I got a cheap acoustic guitar as a gift, but never learned to play it (it's also child-size, so...). I kept it on my bedroom floor against the bookshelf.
At some point I started hearing the strings when I was laying in my bed in the dark and trying to sleep. Not proper playing propably, but just one or two strings at the time. After some time I put it in the walk-in closet but could still hear it. At some point (I don't remember if it was when it was in the bedroom or the storage room), I said aloud that I needed to sleep and that it needed to go away for today. Sometimes telling it off worked, sometimes it didn't, but it kept coming back the next night or a few nights later. At some point I put it in the side attic, which was another door from my room because of the blueprint of our house. I don't know if the music had already stopped at this point or still ongoing, but after that I definitely couldn't hear it anymore.
Around the same age or younger, I sometimes also heard other music. Sometimes it was the thump-thump-thump music from a passing car, sometimes it was sonething else. I only heard it when laying in my bed at night with the lights off, or it could be half-dream I guess, but it's a weird thing to constantly dream about. I told mom and she came to sit in the room, but there of course wasn't anything then. I didn't hear anything either. She accused me of being delusional or something. I was pre-school age or younger there.