"hell," and "haunted."

Conversely, in denying that he is mad, the story’s speaker uses words such as "healthily," "calmly," "wisely," "caution," and "foresight" to describe his own state of mind. Poe uses these words to contrast the reader’s impression of the narrator and the narrator’s own feelings about his mental health.

Through Poe’s choice of words and the choppiness of the sentence structure, he provides the understanding that the speaker is experiencing a chaotic state of mind. In many cases, the lines do not even form full sentences, furthering the sense of frenzy.

In fact, the use of the word “mad” appears twice in the first paragraph alone. Through his diction, including the heavy emphasis on this word, Poe alerts the reader that the narrator fears that those around him believe him to be “mad,” although he himself denies it. In paragraph 1, he asks, “why will you say that I am mad?,” and “How, then, am I mad?” In all, the word mad appears seven times throughout the story in some form—"mad," "madness," "madman," and "madmen."

Poe’s choice of diction to open the story builds the reader’s interest in the speaker’s mental state. The first words are: “True! --nervous --very, very dreadfully nervous I had been and am.” The staccato construction of the phrase and repetition of the words "nervous" and "very" assist in conveying the urgency the speaker feels.

This is not even a full sentence, which also expresses the likeliness that the speaker is undergoing some sort of nervous frenzy. The word “nervous” occurs three times throughout the work, twice within the first six words. By repeating that word at the very beginning, the author builds a crescendo to reflect the chaotic and confused nature of the speaker’s mood.

Moreover, the reader feels as if he or she has entered into a conversation midway. The full opening line of the story is:

True! --nervous --very, very dreadfully nervous I had been and am; but why will you say that I am mad?

Is the speaker responding to an allegation that he is mad? Has someone allegedly been conversing with the speaker for a while for him to acknowledge something the reader said? That the narrator begins the short story by disputing and denying that he is “mad,” setting the stage and mood.

It is not until the last sentence of the second paragraph that we learn what the action in the story is. We finally understand what the narrator is leading up to in his frenzied state of mind when he writes:

I made up my mind to take the life of the old man, and thus rid myself of the eye forever.

Poe's diction throughout the short story "Tell-Tale Heart" gives the illusion of mental instability, lunacy, and terror. Diction is the style of writing and word choice the author uses throughout a piece of writing. Poe specifically uses words like "nervous" and "mad" to convey a sense of hysterical chaos in the mind of the unreliable narrator. The narrator, who is a deranged murderer, utilizes fragmented speech and continually uses words related to sound, which correlate with his auditory hallucinations. The short sentences also create a sense of panic as the narrator rushes to tell various parts of the story. The staccato rhythm of the narrative, with its numerous pauses and repetitions, mirrors the confusion and excitement in the narrator's mind. Poe's use of ominous, foreboding words like "mad," "evil," "dark," "death," and "corpse" create a terrifying narrative that coincides with the macabre subject matter of the story. Several times throughout the story, the narrator pauses in an attempt to persuade the reader that he is not "mad." The repetitive nature of the speaker attempting to convince the reader he is not mad has the opposite effect: the audience becomes increasingly suspicious of his mental instability. Toward the end of the story, Poe uses words like "quick," "fury," and "violent" to convey a sense of panic and dread as the narrator's speech becomes increasingly fragmented while he speaks to the policemen.

Diction refers to the author's choice of vocabluary and style of expression in a story, poem, or any other piece of writing.  In the case of Edgar Allan Poe in The Tell-Tale Heart, the chosen diction is that of a frantic, almost schizophrenic language, in which the speaker is desperately trying to convey to the reader that he cannot handle the prescence of the old man.  Right away in the opening lines of the story, the speaker's fragmented speech gives away his inability to cope with reality as he falls over the word, "nervous."  The speaker repeats some words, like "nervous" several times.  Most sane people will simply tell the story as is, in some intelligable manner, but Poe's narrator is already out of touch with reality.  This can be seen when the speaker insists that he can indeed hear voices and sounds of the beating heart that are not actually there , "I talked more quickly - more vehemently; but the noise steadily increased...but the noise steadily increased!" (Poe) 

The policemen, of course, do not hear anything out of the norm, so this serves to exacerbate the speaker's paranoia and delusional state.  Poe's use of language repetition, "I foamed - I raved- I swore...but the noise arose over all and continually increased. It grew louder, louder, louder!" (Poe), shows just how demented the speaker really is.  He cannot fathom that any of this is happening only in his own twisted mind, and that no one else can hear anything.  Whether it is borne of guilt for killing the old man or not, the speaker begins the story with similar language.

We can therefore make the supposition that the speaker is mentally imbalanced.  Poe uses ominous words, repetition of words, and a frantic, almost stuttering pattern of speech in order to create horror for the reader. He assumes the reader to be an outsider who thinks reasonably, one who can differentiate fact from fiction or reality from delusion.  This use of diction is necessary as Poe weaves a dark tale of madness and suspense.  It is a constant sense of psychological build-up for the reader, as if we are traveling some twisted path inside the speaker's mind.

One particularly revealing sentence comes when the narrator describes how he went about preparing to murder the old man in order to rid himself of the old man's "vulture" eye. He says,

You should have seen how wisely I proceeded—with what caution—with what foresight—with what dissimulation I went to work!

The first thing you might notice is the repetitive structure of the sentence; the narrator uses the phrase "with what" to begin three consecutive dependent clauses. This word choice seems to parallel and even, perhaps, to illuminate his obsessive, even compulsive behaviors. He is obsessed with the eye, certainly, but his compulsiveness—returning to the old man's room every night at exactly the same time until conditions are just right for the murder (the old man's eye must be open)—is even more startling, I think. He seems anxious to address this aspect of his disease, his compulsions, as being, really, "caution" or "foresight" —something really positive—rather than something associated with a disease or a weakness. His diction, here, also reveals that the narrator is intelligent, especially with his use of the word dissimulation.

The term diction simply refers to the author's word choice. Authors can choose formal or informal words, ones with Latinate or Germanic roots, and common or rare terms. Another important choice in types of diction is the degree to which an author uses adverbs and adjectives. 

The narrator of "The Tell-Tale Heart" is insane. Poe conveys this by using very disjoint language, often consisting of short clauses lacking conjunctions (a rhetorical figure called asyndeton). A good example of the narrator's characteristic diction is the opening of the story:

TRUE! --nervous --very, very dreadfully nervous I had been and am; but why will you say that I am mad?

The use of dashes conveys the narrator's inability to think in continuous rational sentences, and thus conveys his nervous character. He uses the words "nervous" and "mad" repeatedly in the story, word choices that focus the reader's attention on his mental state. The use of the adverb "dreadfully" and the use of the past perfect suggest a somewhat educated or intelligent speaker.