I can't listen to music while writing, or I'd stop writing and start singing along. Maybe if it was classical I'd be okay, but I like it nice and quiet. Which is why I need to get up around 4 to achieve that level of silence. Just me and the dogs and the newspaper delivery guy gunning his engine from house to house is all I can hear. :)
I need quiet to write, too, for the same reason (singing along.) But it's amazing how often a song will happen to play on the radio or catch my ear somewhere, just when I'm wrestling with a plot point that needs something>/i> that jogs an idea loose.
Another odd thing that happens to me frequently is waking up first thing in the morning with a song already playing in my head that serves as a theme for the rest of the day.