What are the sound effects of repetition in the poem "The Raven?"

In this poem, there is a great deal of sound repetition, and this repetition has a number of interesting effects on the reader.

For example, there is the poem's perhaps most immediately recognizable sound device, end rhyme; lines 2, 4, and 5 of each stanza contain end rhyme (when the final word of each line rhymes with the other final words).  In the first stanza, then, the words "lore" (line 2), "door" (4), and "door (5) rhyme. 

Further, each stanza also contains internal rhyme, and this is when there are two or more rhyming words within the same line.  Internal rhyme occurs in line 3 of each stanza.  In the first stanza, then, on the third line, "napping" and "tapping" rhyme; in the second stanza, on the ninth line, "morrow" and "borrow" rhyme, and so on. 

But there's more!  In the first stanza, "napping" and "tapping" (3) also rhyme with "rapping" in the middle of the next line (4), and this pattern continues as well; in the second stanza, "morrow" and "borrow" (9) also rhyme with "sorrow" on line 10.  Pretty cool, right? 

The effect of all this rhyme is rather hypnotic.  Whenever a poet trains our ears to expect end rhyme (which Poe does here with its uniformity throughout the entire poem), a poem can take on a somewhat predictable quality, almost as though it lulls us into a sense of security because we can kind of know what sounds are going to come next.  Further, all of the internal rhymes in the third lines and rhymes of those words with a word on the fourth line of each stanza have a similar effect.  We can count on those words rhyming in this poem because they always do, and so we almost feel as though we are also being rocked to sleep by the repetition of these sounds.  Then, when the content and emotion of the poem begins to contrast with these feelings -- either by being completely mysterious (as when the narrator hears a phantom knock at his door) or completely strange (when he begins to suspect that the raven is a messenger from the devil), we are jarred all the more by the discrepancy between the predictability of the sounds with the unpredictability of the meaning.  After a while, because the sounds are predictable and consistent, and because the "plot" of the poem is so weird, they begin to sound kind of creepy, almost chant-like in their repetition.