Final answer:
The sound of the heartbeat in Edgar Allan Poe's 'The Tell-Tale Heart' symbolizes the narrator's guilt and fear.
Step-by-step explanation:
The sound of the heartbeat in Edgar Allan Poe's "The Tell-Tale Heart" symbolizes the narrator's guilt and fear. The narrator hears the heartbeat after committing a murder, and it serves as a constant reminder of his guilt and a source of fear that he will be discovered. The sound of the heartbeat intensifies as the story progresses, reflecting the narrator's increasing anxiety and paranoia.