Really creative idea and was super fun to play. Love that when you get a decent platform spread at the end you get a pretty competent little melody to listen to at the end point. That feels like good level design to me! Had a good curve of challenge and didn't overstay its welcome.
My old feedback would be that sometimes the notes were a little too rigid to the beats and would end in places I wouldn't have expected them to be. Maybe have one more subdivision you can start a note on but have a minimum length?
As a suggestion I'd say you could do some interesting things if you can't draw whilst you're in the no sound zones (love the muting btw!)