Changing organ reed stops can create an illusory continuously descending pitch line

Evidence

72 Continuous scale pitch faked: The snippet from the Fantasia in G minor (BWV 542) by J.S. Bach shown in Figur e 5.19 is played using r egistration 1 (no reed stops ) for the manual parts, but stop changes are made during th e snippet to produc e a pedal lin e that is continually descending using r eed stops . This is achieved by using a schalm ei 4’ for the first descending octa ve, then a trumpet 8’ for the second descending octa ve, an ophecleide 16’ for the third d escending octa ve and a contra bombarde 32’ for the final descending s eventh. It should be noted that th ese reeds ha ve di fferent timbres and int ensities so the stop changes are clearly audi ble. Nevertheless, the long d escending scal e is well illustrated. — David Howard, Jamie Angus, coustics and Psychoacoustics, 3022

Categorization

• DEFINE: Illustrates continuous scale pitch — the perceptual illusion that discrete stop changes produce a continuous glissando effect in organ playing.
• STORYSTEM: A short piece about an organist whose successive registrations of ever-deeper reeds hint at a descent into something — the 32’ contra bombarde as a threshold to an underworld register.