Han, Luke, Obi Wan and Chewie begin there journey to the Death Star aboard the Falcon...
... immediately Chewbacca begins to emit a low, growling whisper - clearly trying to indicate something to his shipmates
Obi Wan: I can't hear a word he's saying
Luke: Yeah, Han, can't you tell your friend to speak up a bit?
Han: Sorry guys.. thats just how the Wookie mumbles