Section 3 Summary

Get out the microscope, because we’re going through this poem line-by-line.

O Ma Rainey,
Sing yo' song;
Now you's back
Whah you belong,
Git way inside us,
Keep us strong….

Back in those short lines, the speaker begins to address Ma Rainey herself. It sounds like our speaker's actually in the audience now.
In an echo of the way that ancient Greek poets used to ask the muses to inspire them (the Odyssey begins "Tell me, O Muse"), the speaker welcomes Ma by telling her that up on stage in a southern town is exactly where she belongs.
Then he asks her to "git way inside us, / Keep us strong."
It is almost as if Ma Rainey has the power to become an inseparable, physical part of her fans' bodies, as if she can jump into their souls and make them feel things. Which would certainly explain why these folks love her so much—they're touched by her music, and it makes them feel better.
Notice how the speaker is using the word "us" instead of me, because everyone is participating in the concert. He seems to feel connected both to Ma and to his fellow audience members.

O Ma Rainey,
Li'l an' low;
Sing us 'bout de hard luck
Roun' our do';
Sing us 'bout de lonesome road
We mus' go….

The speaker keeps asking Ma to inspire him and the fans, repeating the refrain of "O Ma Rainey."
This time, he's making a request. He wants Ma to sing "'bout de hard luck / Roun' our do'." Once again, we're getting hints that these folks don't have awesome lives.
And they turn to Ma Rainey to make it better. But what's interesting here is that they're not asking her to distract them from their troubles—they want her to sing about those troubles. Maybe she has shared them, and maybe that brings them solace.
The speaker also wants Ma to sing about "de lonesome road / We mus' go." Sterling Brown was really into the metaphor of the road; he even called his first collection The Southern Road.
Sure, the literal road that the fans travel on to get to the show is anything but lonely; there are tons of people headed to the show, after all. But we're thinking the speaker here is talking about a more figurative road here, like the journey of life that everyone has to go through alone.
Sterling Brown is weaving a sense of togetherness that comes with attending a concert with hundreds of similar fans, to listen to a singer sing about your lives with the isolation that comes with the hardship of plain old living. Nifty, right?