Mix colors and textures of noise. Everything is generated live, with no audio files.
How loud the mix is at each pitch, bass on the left. Drawn relative to its own peak. Brown tilts steeply down, violet tilts up.
Sound is generated in your browser. Playback is set up to continue with the screen off, and your lock screen gets play and pause controls. Phones differ, so test it once before you rely on it overnight. Keep the volume low.