I worked in an open office situation once with a co-worker across from me who listened to sports talk radio all day - no headphones. I literally can't imagine a more distracting work environment.
Maybe you could have requested him/her to use headphones. Many a times in a situations similar to above I have requested my coworkers to use earphones, and usually they would comply.
Eventually, and amazingly we actually became decent friends... eventually. In the early days it was a matter of picking my battles, and there were other more important things to work on. (Hard as that might be to believe.) So for a while I just put my headphones in and tried to tune it out.
(Initially I just asked him to turn it down, and I don't recall the exact response, but it was probably approximately, "No.")
