I think that that is your consequence for missing the shot.
Viewing post in Show Stopper jam comments
King is correct! When you hit a button without a note being there, you get stunned. It was done so it would not be possible to mash the keys to get every note. The stun time may be too long, as missing during the barrage is nearly a instant death. Thanks for the feedback, I try to improve the conveyance in my games over time.