Poe used a specific term for the writing style he used; he called it Arabesque, which in literary terms means a prose style intended to cause feelings of unease and discomfort in the reader. Poe's writing style thus uses powerful descriptive words and phrases, and in this case, is couched in the frame story of a man confessing his crime to police. For example, when the narrator is explaining his plan, he states:
You should have seen how wisely I proceeded -- with what caution -- with what foresight -- with what dissimulation I went to work! I was never kinder to the old man than during the whole week before I killed him.
(Poe, "The Tell-Tale Heart," xroads.virginia.edu)
Poe's descriptions here are meant, by the narrator, to reassure: see, he is not mad, simply thorough and cunning! However, in the telling and in the narrator's protestations that he is sane, he comes across as far more insane than he would had he simply confessed. The prose is almost, but not quite, "purple," using unnecessary words and synonyms, but instead each word is chosen carefully and specifically to add discomfort to the story. Poe uses this style in other works, most notably "The Cask of Amontillado" and "The Premature Burial." Poe's writing also contains influences of gothic, melodramatic, and tragic styles.
Edgar Allan Poe uses many different literary devices in "The Tell-Tale Heart." He begins the story with the use of irony. In trying to prove to the reader that he is not mad, the narrator admits to having an acute sense of hearing. He states that "I heard all things in the heaven and in the earth. I heard many things in hell." It is ironic that as a means to trying to prove his sanity, he reveals that he hears voices. Irony is used at the end of the story when he and the officers sit in chairs on the floor where the old man's body is hidden.
Poe also uses imagery when he describes the old man's eye. The narrator says "One of his eyes resembled that of a vulture -- a pale blue eye with a film over it."
He uses more imagery the night of the murder.
" So I opened it -- you cannot imagine how stealthily, stealthily -- until at length a single dim ray like the thread of the spider shot out from the crevice and fell upon the vulture eye."
In the following passage, Poe uses a simile to compare the beating of the old man's heart to the beating of a drum before battle.
"It increased my fury as the beating of a drum stimulates the soldier into courage. " The heart beat caused his fury to increase just as a drum beat increases a soldier's courage.
Poe also uses ironyin this line because the narrator is comparing his furry to a soldier's courage.