I don't know. I had the idea for this for forever.
You can press down to go half-speed, left and right to scan through the parts of the chorus.
The audio and graphics go out of sync and I've coded to accomodate for this, but it seems like it's unpredictable. You'll probably hear a glitch as it loops. On my machine the graphics are like .5% slower than the audio. IF YOU REALLY WANTED TO there is this M variable in the code you can tweak.
EDIT: Alternate self-corrupting version.