THE SCIENCE AND APPLICATIONS OF ACOUSTICS - H. H. Arnold ...

548 18. Music and Musical InstrumentsFigure 18.34. Schematic of the elements of the modern organ (from Olson, 1967).and organ consoles, it should be mentioned here, are not standardized. The organmay be constructed with one or more manuals and with or without a pedal keyboard.In a five-manual organ, the functions of the manuals are as follows: The first (or thelowest) controls the pipes in the choir organ; the second controls the pipes of thegreat organ; the third controls the pipes of the swell organ; the fourth controlsthe pipes of the solo organ; and the fifth controls the pipes in the echo organ.The pedals control the pipes in the bass organ. In a number or more elaborateinstallations, other instruments have been added to pipes (e.g., gongs, cymbals,gongs, drums, etc.). Yet other installations contain as many as seven manuals. Thetypical pipe organ in use today has two to five manual keyboards and a pedalkeyboard.It can be seen from the schematic of Figure 18.34 that the organ is a combinationof several organs, each organ having a different kind of pipes. We have earlierdescribed the flue organ pipe and the reed organ pipe. Pipes can be classified intofollowing basic groups: the diapasons, flutes, strings, and reeds. The more commonflue and reed pipes are illustrated in Figure 18.35.In the evolution of the organ, it was found that the tones could be improved bygrouping a set of pipes to sound simultaneously by depressing a single key. Thuseach key can represent any number of pipes, and each combination of pipes iscalled a stop, a term which is also applied to a knob along the sides of the console.Each stop knob controls a specific group of pipes.