When i studied traditional animation (drawing), I was always reminded not to listen to music while working... I picked up the habit even while coding and doing anything basically. I also had a problem of concentrating or being in the zone while listening to music while working... however, as of recently, I've tried experimenting with listening to music while working, again. I found that I have no problems with concentration anymore, and I find it quite enjoyable working along with music - BUT, I found out that I do less work while listening to music as opposed to sans music. Not by a large margin, but I think I'll listen to music from now on, since it's more enjoyable experience.