[BillGoates]

For me personally, I couldn't work without music. It blocks out environment noise. In a silent area it's like every small sound is amplified tenfold. It could be I'm different, but I had very productive weeks, while on the other monitor Farscape was playing for the nth time.

So I would say, let them choose for themselves what works best. Loosing concentration once in a while because of the music might be a natural stopping point, and listening to music for a short time gets the brain rested enough for a next period of concentration.