ive found its a more squeaky rattle, and its from where the top of the back edge of the door meets the seal when its closed. as horrible as it sounds, try rubbing some saliva on it before you close the door, it works for me as a temporary fix but am looking to find a way of softening up the seal again.
Tommy
p.s - i only resorted to the saliva as with the 4 hour commute i am doing at the moment the noise in my ear was driving me insane!