who is the narrator and how is he revealed?

Chief Bromden narrates in the first person. He tells the story as it appears to him, though his objectivity is somewhat compromised by the fact that he suffers from paranoia and hallucinations. His unusual state of mind provides metaphorical insight into the insidious reality of the hospital as well as society in general. Because he pretends to be deaf and dumb, he is privy to secret staff information that is kept from other patients, which makes him a more reliable narrator than any other patient would be.