Wow! Clean platformer movement aside what a unique mechanic! I tried at first and didn't get past the 3rd gate. I simply had to come back to the game and try again though because it was such a cool idea! Got a lot farther on my second attempt :).
If I had one suggestion it would be to add a beginner mode where the sounds are associated with the colors. Then people like me can fully experience the game and learn some some basic chords along way. Note: I don't know if chords was the right word :X