The narrator in Edgar Allan Poe's short story, "The Tell-Tale Heart," wants only one thing from his audience. He wants his audience to believe that he is not mad. In the first three paragraphs, he brings up his mental state twice.
In the opening paragraph, the narrator questions why his audience believes him to be mad. Curiously, he assumes that his audience has already heard of him and the murder, probably because he is talking to his doctor or a prison doctor. He is already on guard against his audience. In the third paragraph, the speaker, again, accuses the audience of thinking he is mad.
Essentially, the narrator continually reminds his audience that he is not mad. He wants, more than anything, the audience to believe in his sanity. He is not concerned with the fact that he murdered the old man; instead, he only wishes to be considered sane.