While Poe’s primary poetic devices in “The Raven” are the rhyme scheme and meter, he also makes ample use of word sounds and sound repetition to lend additional power to his language. On multiple occasions, this manifests as alliterative phrases appearing as early as the very first stanza:
While I nodded, nearly napping, suddenly there came a tapping […]
Through a mix of initial alliteration, or a repetition of sounds at the beginning of a word, and internal alliteration, or repeating sounds in the middle of a word, Poe uses the /n/ sound to give shape to his line and thus mimic the gentle motion of nodding to sleep.
Later, Poe uses a repeated /s/ sound to evoke the shifting of fabric:
And the silken, sad, uncertain rustling of each purple curtain[…]
Here, the sustained /s/ sound rustles through the line in the exact manner of the purple curtains within the story.
In still another example, Poe uses an alliterated /fl/ sound to emphasize the abrupt arrival of the Raven into the narrator’s chamber:
“Open here I flung the shutter, when, with many a flirt and flutter,
In there stepped a stately Raven of the saintly days of yore;”
In this case, the momentum of the /fl/ sound in an initial alliterative position carries a certain fluttering sound, mirroring the movement of the Raven himself into the room.