replied to earlier:
Often silence, for me. I could create a (narrow) bell curve of problems where I listen to music. If I'm doing light enough work then I don't tend to listen to music, probably just out of habit - but as I approach problems of a certain complexity then I do prefer music. I just find that complexity band is narrow and past it I need to turn off the music.
I would like to widen my music band. My preference is usually ambient - I like Gaussian curve and Hiroshi Yoshimura