Three forms represent the low, middle and high voices of the music. Use their labelled buttons and arrow keys to move them.
bluebucketSTUDIES / 003

DRAG A FORM / HOLD TO OPEN

Headphones reveal the space

Aphex Twin — Stone in Focus · Supplied MIDI study

Sound starts only when you enable it. Use Tab to focus a voice and arrow keys to move it. Hold Space on a voice to open its tone. Elsewhere, Space pauses. D changes appearance, H hides controls and F toggles fullscreen.