With musical references right there in the title, it shouldn't come as a surprise that "The Guitarist Tunes Up" sounds kind of music-y. This musical quality is due in part to those strong end rhymes and meter (see our "Form and Meter" section for more on this), but it also comes from some more subtle sources as well.
In addition to all that rhyming, Cornford uses consonance to create a kind of musical sound. Take a look at line 4:
Command both wire and wood
Hear those repeated W and D sounds? That's our old pal consonance at work. This helps the music carry through the lines rather than only showing up in those heavy rhymes between the end words of one line and another.
But Frances didn't stop there. She decided to throw some good old-fashioned repetition into the mix:
What slight essential things she had to say
Before they started, he and she, to play.
The repetition of she in lines 7 and 8 really stands out when we hear the poem (and it stands out visually as well). In an eight-line poem, any repetition is going to get noticed. This one comes in the poem's final couplet, so it gets even more attention. The sound of the word she in line 7 is still ringing in our ears when we come to it again in line 8. It's even amplified by the he that precedes it (very close in sound and visually only one letter away from actually being she). The repetition functions kind of like a repeated note or chord in a song, tying things together and making the song feel like, well, a song.