MIDI playable Shepard tones with graphic display
Receives MIDI notes to play shepard tones. Tones created with octave harmonics whose amplitudes are scaled in a bell curve as illustrated in center panel display, which reacts to keyboard input. Shepard tones create illusion of endless ascent/descent while never actually leaving one octave. Illusion works better with slow chromatic scales. Fast movement and leaps will be less convincing. Expectations have influence on perception: If you play up you'll hear it go up, if you play down, you'll hear it go down, etc. Success also depends on speaker response and room acoustics. All MIDI note numbers are converted to range 60-71. Sound can be made lower/higher by adjusting the center frequency of the pass band with the "cntr frq" knob.
Because Shepard tones sound like an organ, I've treated it like one and kept the instrument conservative and simple. There is no velocity repsonse, there is only a switch for attack hardness and a level control which is good for mod wheel. Users can easily change this and add whatever envelopes and other features they like. I've also connected it to the Lezlie effect from the library, which makes it musically useful, and the illusion still works.