The rhythm of this poem makes us feel like we are walking through the woods with the speaker. We can hear his footsteps in the steady rhythm and rhyme, with the occasional diversion to look at the colors of a particularly brilliant tree. With lines a little shorter than the average metrical poem (a poem that follows a set pattern of rhythm) and stanzas a little longer than the average rhyming poem, the sound of "The Road Not Taken" isn't like many other poems, just like the speaker, who tries to be different from everyone else when he chooses his path.
Still, we can hear in the sound of the poem that the speaker isn't speeding ahead, but proceeding slowly and carefully, as he's not quite sure he's on the right path. The most obvious indication of this hesitation in the sound of the poem is in the last stanza, where the speaker repeats the word "I." This sounds like the speaker has stopped walking for a moment, and even the birds in the wood have stopped to listen to how the speaker will end the poem.