How well can you control your volume? ++++++++++++++++++++++++++++++++++++++++++ Hum/Make Noise louder to go higher. The difficulty changes the player hitbox. If you don't want to use noise, you can select the "Hold" option at the bottom right corner. Holding is significantly easier though, so I recommend using your voice. This may be tricky when you start, but you will get the hang of it eventually. I recommend humming.
For the @tcscer_Kavin 150+ [Win 20+ follows]GAME JAM. Music from Freesound