If the sound of this poem were a Starbucks beverage (bear with us here), this would definitely not be the caffeinated and sugared rant of a venti caramel latte. It would probably be more like a smooth and subdued tall chamomile tea. The volume is turned down in this poem. There is no rhyme, either. Only very subtly and carefully does Dove include some alliteration and assonance in the third stanza.
There you can hear the repetition of the hard C sound in "clean," "carved," and "camera." And the long E sound is followed by the similar long (as well as short) A in "clean flame of her gaze / carved by a camera flash." We also get some alliterative D sounds with the repetition of "doing" in line 7. These sounds pile up in the third stanza to subtly mirror what's happening in the poem (the jostling of the photographers around Rosa Parks). The focus on Parks, though, is a calm one, not a frenzied furor. Dove uses these sound techniques, then, with a light hand—just enough to carry our ear effortlessly from line to line. Mostly, Dove doesn't want to distract the reader with fancy sound works; she wants this poem to sink in slowly and powerfully, with Parks's own dignified character and grace.
You might also notice that most of the lines are of equal length, but pay attention also to the length of the words. There are only three words in the entire poem that are 3 syllables (can you find them?). All of the other words are 1 or 2 syllables. Short words and short lines—and often short sentences ("Her sensible coat." and "That courtesy.")— create a slow and steady pace. We're meant to savor this scene with Parks, to take a "seat" and look back into history with Dove's steady voice as our tour guide.