Many years ago in my first tech job, before the ipod, I had a sony walkman where I would change the batteries more often than the tape.

This one tape would be on continuous loop for days and weeks at a time. I had never been more productive in that job. But in effect I wasn't listening to music at all I was blocking out the distractions from the open plan office we worked in.

Since then I've experimented and found that ear plugs work best of all.