 During filming, Peter Mayhew (II) (qv) actually spoke English  dialogue for Chewbacca so that his characters conversations with  the actors would seem more natural. In post production; his dialogue  was dubbed into what we see now Chewies growls and barks. A clip of  Chewbaccas voice before dubbing in the Death Star control room  scene is shown on the documentary included in the new 2004 DVD  release.