The speaker of this short poem describes himself as a kind of listener for hire. His "office" isn't a room but the ear, and his work is taking in whatever voice turns up at midnight, a voice already "oiled and drunk." The image makes the blues singer a late-night confessor, someone who hears other people's pain after everyone else has gone to bed.
In the second stanza, trouble itself becomes the singer, performing in a "melancholy method," as though sadness has its own careful technique. The last line is the most striking: "the one bed is for her." Trouble isn't just a visitor here. She gets the only bed, which suggests the speaker has no space left for comfort or rest. The tone is weary, wry, and a little resigned. Nothing is solved, but the speaker seems to accept that sorrow has moved in, and that listening is both his job and his company.