Situational Irony: Narrator's nature
The narrator mentions himself as a very timid and humane person. He was even the butt of his friends’ jokes because of this nature. Even so, his parents encouraged him to have such a disposition and keep animals of his liking. It is ironic that such a person would start committing crimes—not even out of problems or need, but merely for the thrill of it.
Dramatic Irony: Narrator's arrest
The narrator is confident that he would not be apprehended since he had concealed the wife’s body so well in the walls of the cellar. In his boldness, and to make the police sure about his non-involvement by appearing natural, he mentions that the walls of the cellar are too strong and raps on the spot behind which his wife was buried. From the walls come a muffled sound, which leads the police to discover the dead wife and the black cat. Thus, the narrator ironically gets himself arrested in a bid to appear innocent.
