We notice that in each stanza the lines 2;4;5;6 end in a trochee in which the final unaccented syllable has been dropped.
What do you think Poe ended these lines with a stressed syllable?
"The Raven" by Edgar Allan Poe
The poem contains trochaic octameter. You are perceptive to notice the meter, in which the final unstressed syllable is missing in lines two, four, and five of each stanza. The sixth line of each stanza contains three trochees and an extra stressed syllable at the end.
Like all lyric poets, Poe uses rhyme and meter to create rhythm and mood. "The Raven" has a singsong effect, and the long vowels and extra stressed syllables help to unify the effect of the poem.