Reeds are inserted for a 43-tone-to-the-octave scale. Thus, an acoustic octave covers that many keys and reeds, successively, and measures some three and a half keyboard octaves. The scale is in just intonation, and each tone is a frequency ratio to a fun
University of Wisconsin.
A pedal-pumped reed organ with sub-bass, adapted to play all the chromatic pitches in Harry Partchs 43-tone per octave source scale. The instrument uses a standard piano keyboard, brightly painted to indicate harmonic relationships between the various pitches.