I would say that these lines, from "Tell-tale Heart", by Edgar Allen Poe, make him seem less reliable. This is because he is speaking very frantically, as though he is panicked (which he is), and it makes him seem crazier. He appears to be having a delusion because "I can hear sounds that I've never heard before, I can hear sounds from heaven; I hear sounds from hell!". think that this line makes him most notably crazy and unreliable.
Hope this helps! :)
