An author use of a disturbed first person narrator can help create in a gothic story suspense and tension.
Gothic stories are characterized by the moods of suspense and tension. This is because the setting tends to be dark and dreary and mysterious, and we don't know what's going to happen next. If the narrator is talking is telling the story from the person point of view, and his or her voice is disturbed in addition to that, the mood is amplified.