When I was in high school, my math teacher would play Mozart during tests, claiming it would help us. It would drive me crazy, and I doubt that my grades improved as a result of the distraction.
For what it's worth, I have a BMus in Piano Performance. I love music... but never as "background noise"!
Music is never a background to me. I will occasionally switch music on while working, but with the specific purpose to switch my mind. Usually either when I am trying to work out the best solution to some problem and I need to get away from it for a second or when I am task switching.