Time and Heartbeats
Many of the narrator's hyperbolic observations center on time and sound. "A watch's minute hand moves more quickly than did mine ... for a whole hour, I did not move a muscle," he states as he watches over an old man he ultimately murders. When he imagines the old man's heartbeat, he agonizes, "the sound would be heard by a neighbor!"
Hyperbole Shows Obsession
Poe, according to New York University's literary database, uses "frenetic diction" to underscore the lunatic's obsessive perceptions. This hyperbole-soaked mentality is nowhere more evident than in the story's finale, when the madman "foamed, I raved, I swore" during a quiet conversation with police, as an ear-splitting imaginary heartbeat leads him to distraction and finally confession of his murderous deed.