I had a similar thing a few years back. Basically, I used to sit in my room and have music on. Now i'm not inconsiderate, I checked myself by walking around that it wasn't carrying outside the room. With the door closed it was inaudible.
However this didn't matter to the jobsworth officer living at the end of my hall (a good twenty doors away). Apparantly he could hear it and that was that. I tried to prove to him that it wasn't me by testing to see if he could tell when it was on or not. One night I got woken up at 1am by him ranting that I was "keeping him up". How am I doing that with everything switched off, in a dark room, in bed?
In the end I got a letter telling me I had a "meeting" with the head of halls about it. I went around my floor, the one above, and the one below, and got near a hundred signatures saying that nobody had ever found it a nuisance. I got the two people either side of my room to come to the meeting to back me up.
And despite hearing all this, that same "officer" (who was one of the people in the meeting) was aggressive and adamant that I was totally in the wrong. The result? They fined me £60 for it.
One trip to the CAB later and the ******* recinded it. He also opened himself up for a whole load of trouble as well, it turns out that students don't take kindly to this kind of thing.
The summary? Fight it. The Uni are probably just trying to make a quick buck like everyone else, don't damn well let them.