Hearing this poem out loud is like overhearing one end of a conversation. It's not really a prepared speech or anything quite so formal. Nope, it's more of a sneak peak into someone else's stream of consciousness. "Stream of consciousness" means an uninterrupted flow of thoughts, which is how the speaker attacks this assignment. His thoughts seem to flow randomly out onto the page, creating an informal, conversational tone both in terms of the poem's content, but also in terms of its sound.
As we discuss in "Form and Meter," there are many points along the way that the poem's content points to its informal, conversational nature (like the repeated use of the phrase "I guess"). But how does the sound of the poem accomplish this same impression? Take lines 19-20, for example, when the speaker is addressing Harlem:
hear you, hear me—we two—you, me, talk on this page.
(I hear New York, too.) Me—who?
By the end, it's like, okay, we get it! Things are a bit confused. But the sound of the line also helps get that point across. For one, the meter of the line is funky, a series of short, syllabic bursts. Sonically, this line stumbles. There's no flow to it at all. And that is pretty much the point. As the speaker contemplates that complex intersection of his self, his environment (Harlem and great New York City), and his writing, his stream of consciousness hits a rough patch.
Still, there is some connection at work, though, and the sound of these lines reminds us of that. The rhyme here is inconsistent (which is in keeping with the speaker's confusion), but it is present in the words "you," "two," "too," and "who." We also get the repetition of "me" in these lines, which adds another rhyme. Amid the stumbling rhythm, there is some symmetry to be found here. So, the use of sound in this moment in the poem mirrors the speaker's confusion, but also suggests a strong thread of connection running through him and his environment.
The sound of this poem also mirrors the speaker's thoughts with the fun alliteration of "Bessie, bop, or Bach," in line 24. We mean, who wouldn't be happy when discussing their favorite records? The speaker's enjoyment comes out in the very sound of the poem, with a bevy of bouncing B sounds to bedazzle us.
So, there is a lot in this poem that gives us insight into the way this speaker is approaching his assignment, and what that approach might say about his experience and personality. We're getting his mind at work on the page, and the sound of the words turned up by that stream of consciousness plays a complementary role in communicating that same idea.