he hears is the old man's heart beating, and the terror of that after he knows he has killed the old man is too much for him. He tears up the boards and admits to his crime. The watch is the heart, and the beating of it is what pushes the narrator to confess.

The narrator is afraid of his own death, and the watch he describes is a symbol of human mortality, most especially his own. We learn that the narrator hates the old man's eye, which he calls a "vulture eye." Vultures are very much associated with death, as they feed on carrion, as is old age and, perhaps, the disease which seems likely to have caused the old man's eye to change: cataracts. Cataracts tends to affect older folks who are, because of their age, closer to death. The narrator seems to hate and fear the things about the old man that remind him of death rather than the old man, himself.

On the night he eventually murders the old man, he says,

Presently I heard a slight groan, and I knew it was the groan of mortal terror. It was not a groan of pain or of grief--oh, no!--it was the low stifled sound that arises from the bottom of the soul when overcharged with awe. I knew the sound well. Many a night, just at midnight, when all the world slept, it has welled up from my own bosom, deepening, with its dreadful echo, the terrors that distracted me. I say I knew it well. I knew what the old man felt, and pitied him.

The narrator specifically identifies the old man's fear of death and dying, and he says that he is able to do so, essentially, because he has felt that same terrible fear many times himself. It has kept him awake countless nights. However, he does not seem to realize that his fear of the old man's eye is connected to that fear of death. A short while later, he discovers that the man's eye is open, and, he says,

there came to my ears a low, dull, quick sound, such as a watch makes when enveloped in cotton. I knew that sound well, too. It was the beating of the old man's heart. It increased my fury, as the beating of a drum stimulates the soldier into courage.

Have you ever heard another person's heart beating from across the room? I sure haven't, but I know I can hear my own heart beating fast and hard when my adrenaline is racing (as the narrator's surely is). It is not the old man's heart that he hears; it is his own as a result of the excitement he feels, an excitement that he describes as urging him onward like a drum does a soldier. We know this must be the case when he hears the exact same sound again, after the old man's death. He says,

It was a low, dull, quick sound--much such a sound as a watch makes when enveloped in cotton.

This cannot be the old man's heart because he has been physically dismembered and placed beneath the floorboards of the home. We now know the sound to be the narrator's own heart, the sound of which he associates with a watch, as if to indicate his fear of his own mortality, his knowledge that, one day, his time will be up.

In Edgar Allan Poe's story "The Tell-Tale Heart," one of the key symbols is the watch. The narrator refers to the watch at different points in the story and talks about the sound of the ticking. He also discusses the heart beat that he believes he hears which sounds like a watch enveloped in cloth. The significance of the watch in this story is that it adds tension by making the reader aware of time moving along. It makes the reader wonder if the narrator will get caught from the murder of the old man. And it represents the heart beat that can either stand for the dying of the old man or the narrator's guilt at the end. Poe uses this symbol to make the events of the story have a stronger impact on the reader. As the clock ticks down, so does the time left in the story for the narrator to finally confess.

In "The Tell-Tale Heart," Poe uses the watch to create an auditory (sound) image. He likens the beating of the old man's heart, for example, to the sound of a watch "enveloped in cotton." This is effective in enabling the reader to imagine the sound of the beating heart.

Looking deeper, however, and the watch represents the narrator's guilty conscience after he has murdered the old man. When the police arrive, for instance, the narrator begins to hear this noise again. At first, this sound is "low" and "dull" but, as the narrator's anxiety grows, the sounds intensifies:

"I talked more quickly --more vehemently; but the noise steadily increased."

By the final paragraph of the story, the narrator can no longer bear the sound. It is symbolic, therefore, of his growing need to confess to his crime and functions to bring the story to its dramatic climax.

In Edgar Allan Poe's "The Tell-Tale Heart," the unreliable narrator creeps to the old man's chamber to peer upon him while he sleeps for seven nights.  On the final fatal night, the narrator fumbles with the tin piece on his lantern, and the old man sits up in bed, listening for an hour.  The narrator compares the old man's vigil in the darkness to his own, in which he has sat up "night after night hearkening to the death-watches in the wall." 

Death-watches are a type of beetle, which can make a tapping sound, and in more superstitious times, people associated the tapping noise of the death watch beetle as a deathly omen.  Poe uses the superstitious nature of the death watch beetle and its eerie tapping sound in the walls of the home as foreshadowing for the thumping of the murdered old man's heart which will later torment the narrator.  In fact, Poe leaves the reader wondering what the narrator really heard:  the slow, rhythmic tapping of the death watch beetle or the actual murder victim's heart.  Perhaps the narrator's paranoia led him to mistake the sound of the insect in the walls for the beating of the "tell-tale heart."