Took me while to figure out what to do, but after that it was quite cool figuring out what sound happens when (as a non-musician). One bit of polish I personally would of liked is when you press an ear button (sorry for not knowing the terminology), but you already have another one selected, switch the selection to the new one instead of doing nothing (if that made sense).
I absolutely love the visualizer in the background and the music is phenomenal, good job!