you need to select and calibrate a microphone in the settings (using the "Microphone Calibration" button - which tells you to use 4 different levels of volume through your mic for 5 seconds each).
it should automatically bring you to that screen on your first boot, but i might've messed that up :/
after that, the "intensity" of the waves is dependent on the volume that comes through your mic. if no red waves come out of your character upon loading a room, try pressing R to reset the level a few times - it's a bug i didn't manage to hammer out in time