Where is an example of irony in the tell tale heart?

An example of irony in Edgar Allan Poe's "The Tell-Tale Heart" occurs when the narrator insists on his sanity while describing his meticulous planning of the murder. He believes that his heightened senses, particularly his acute hearing, validate his sanity, yet they ultimately lead to his downfall. The irony lies in the fact that his obsession with the old man's eye and the murder itself reveals his madness, culminating in his confession when he can no longer bear the sound of the imagined heartbeat.