A good idea but it is too hard. Maybe because predicting the wave motion is almost impossible. A common solution is to give the player a visual cue when to hit the correct note, like in Guitar Hero. The music is very good, by the way.
Viewing post in Waves Don't Die jam comments
Based on your feedback, I have updated the game to provide some help for both predicting the waves motion and give a visual cue for the player. I have added two black lines on each side to help the player know when to press. I've also made the wave particles change based on its state, Green for slow speed, Blue for when it is about to change speeds soon, and Red for fast speed. Looking out for blue will allow the player to predict when the speeds will switch.