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"!
I recently discovered I have a tendency to unconsciously listen to everything around me and analyze it, aggravating my mental fatigue. now I try to be careful and avoid doing that.