Why Is The Sound Of A Pipe Organ Better?

by Scott R. Peterson, President
Peterson Electro-Musical Products, Inc.
Alsip, Illinois

Pipe organ builders are often asked what makes the sound of a pipe organ better than that of electronic organs which utilize today's sophisticated digital sampling technology. After all, if a high-tech recording is made of an organ pipe, and measurements show that the wave forms produced by playback of the recorded note look like the wave forms produced by the actual pipe, what difference would be heard? Is the difference in sound between an electronic organ and a real pipe organ so subtle that only trained musicians would appreciate it?

Clearly, a pipe organ has many tangible advantages over electronic organs, such as visual beauty, longevity, and usually a superior quality of materials employed. The pipes, chests, console, structural and decorative elements are built with a level of craftsmanship that has grown rare. Modern solid state switching, combination action, MIDI interface, and other control systems designed specifically for pipe organs offer every conceivable feature and convenience as required by even the most advanced organists. The most popular of today's solid state control systems allow abundant flexibility for future expansion or modification of the pipe organ to meet needs years or decades into the future. Somewhat less tangible but very real is the feeling one gets that a pipe organ is a permanent, high quality investment in value rather than a device that will be replaced in a decade or two. But what about the difference in sound?

The key to this lies in the interaction of sounds that one hears when many notes on multiple ranks of the pipe organ or electronic organ are played together, and especially when this is further blended with the singing of human voices. A good recording of a single note played through a speaker may sound almost identical to the actual pipe that was recorded. The authenticity of electronic organs played one rank at a time can be very impressive indeed. However, a very significant difference would be perceived by most people in a typical audience if the same hymn or recital piece were to be played first on an electronic organ and then on a pipe organ. Many would describe the difference as more"thrill" or "fullness of sound" from the pipe organ (not to be confused with greater loudness).

Scientists and engineers have determined that the musical sounds we hear are collections of many separate simple vibrations called "partials" reaching our ears after being produced by vibrating devices like strings, wood or metal bars, reeds, or air columns in tubes such as with organ pipes. Rather simple sounds like those of an orchestral flute or flute organ pipe consist of only a few separate partials occurring simultaneously, while richer or more complex sounds like that of a violin string or a viola organ pipe are made up of a large number of partials.

The partials of each note of a particular instrument or a particular rank of pipes are usually related to each other in specific ways. For example, each pipe in one rank may be characterized by the slowest vibration (called the fundamental) being joined by another partial three times as fast and another five times as fast, with these higher two partials (called the third and fifth harmonics) having a specific pattern and time rate of increasing and/or decreasing loudness after the note is initially played and then held. These dynamics can be carefully duplicated for each note of an electronic organ, creating convincing substitutes for one real pipe at a time. The reason for the profound advantage of the pipe organ begins after these sounds leave the source and travel to the listener's ears.

When several musical notes are produced by separate organ pipes, each in their own location, every partial of each note creates its own sound waves in the air, substantially independent of all other sound waves. Each individual sound wave reflects from and may be partly absorbed by the ceiling, walls, furniture, and any other element in the room so that it takes it's own amount of time to reach the ears of a listener. Because the human brain is so extraordinarily capable, the differences in time that every sound wave takes to reach the two ears and the "shading" of the listener's head between one ear and the other are actually perceived and help to give a feeling of complexity to the sound. This desirable effect is compounded when potentially dozens of individual pipes are played simultaneously as the organist builds a chorus of sounds. In contrast, each of a few loudspeakers on an electronic organ produces a single sound wave that is the electrically combined total of all the partials of all the notes played through it. The complexity of reflections within the room and the corresponding fullness and beauty of the resulting sound is much reduced. The sound from the electronic organ tends to be more directional. It is easy to point to the location of the speakers whereas the pipe organ sound seems to fill the room from all over.

A further difference is that the electrical combining of partials from the same note of more than one rank, or "coincident partials" of different notes, leads to certain components of the total sound being louder and some softer than when the sound of separate notes from independent pipes are combined in the ear. If the partials being combined electrically are very slightly different in pitch, an unnatural "beating" sound results. These factors often lead to a peculiar distortion common in many electronic organs, and at the very least the electrical mixing creates a less pleasing blend of sounds.

While this explanation may seem complicated to some and abbreviated to others, suffice it to say that the room-filling, supportive, thrilling sound of an actual pipe organ may be appreciated by casual listeners as well as aficionados of fine music. The tonal advantage of a collection of pipes over a few loudspeakers is based on scientific principles. Just as listening to a CD recording of a symphonic performance is not the same as attending the live performance, there is just no substitute for an authentic pipe organ for providing meaningful, fulfilling music.