Any slightest noise will disturb me, but loud music will allow me to focus because it blocks out other noises, I guess it is the same for most people with ADD though. One of the fans in my case is making a grinding noise and it is really disturbing me, so I had to crank up my music.
I’ve always been able to concentrate more with music though, when reading a book, if there is music on then I can concentrate, but if the television is on I can’t really focus. I don’t know why that is, maybe because with the television I am trying to stay focused on the story on there rather than anything else I am trying to do.