If one were so insensitive as to bring a stopwatch to a service, one would find that the organ spends the majority of its time supporting, accompanying, and leading the human voice. Therefore, an organ used in worship should have the right quantity and quality of sound relative to soloists, cantors, song leaders, liturgists, adult and children's choirs, and congregations. These requirements are not expected from any other instrument or performer. Books and journals that deal with organ design seldom address this topic, yet most organists perform in sacred rather than secular settings.
An organist's training usually involves a course in "service playing," and our best teachers are masters at giving students the ability to carry out many musical tasks. But the art of accompanying is difficult to teach, and difficult to learn. Learning to play a service does not always imply a knowledge of what is needed of the organ and organist for accompanying the human voice.
Organbuilders and consultants seldom study the organ as an accompanimental instrument, or from the viewpoint that its main task is associated with the singing human voice. Such concerns are often looked down upon as being un-academic or intellectually weak. Perhaps some innate or accidental character of the organ makes it suitable for singing. Is there some trait in the organ- builder that attracts him to the task of the worship instrument so that one unconsciously leans in the direction of the human voice? I think not. I have heard many church instruments which had no ability to work with the human voice, and many others which were at the height of musical competence for doing so.
In the 1950s, a famous organist stated that organ design should conform to certain very specific rules which had recently been codified after studying a few historic instruments. It would then, automatically, be perfect for a church service as well. In many cases this would be true, but the argument was putting the cart before the horse; a subsidiary requirement determining the primary.
The organbuilder is expected to design and build a church organ, but nowhere in his training and study does the builder encounter any information, criteria, or guidelines about how the instrument actually functions in its main role.
The church organ may be an example of an instrument which developed a particular musical task (supporting singing) by accident, only to have that task become so all-encompassing and complete that it was assumed to be natural, and then taken for granted. Could it be that some styles of church singing developed in response to the character of the organ (or the organist) -organ and singers developing together and adapting to the strengths and weaknesses of the other? Symbiotic in the best of situations; at odds in others. A mysterious coequivalency now so obvious as to be undiscussed.
Some organ committees tell the builder that they want a worship instrument (whatever that is) rather than a recital instrument (whatever that is). Their instincts are correct from their point of view, though neither the committee nor the builder may know exactly what is meant. I do know that the first thing a committee will do when such a worship instrument is installed is to schedule a recital on it.
In the opening paragraph. the organ's primary task was divided into the roles of supporting, accompanying, and leading the human voice to sing. Each is a different aspect and each is important and comes into play at different times in a service. The organ has a variety of colors, timbres loudness levels, and tonal characters. The skilled organist with a well-designed organ knows how to use these resources for success.
I doubt that any two organbuilders think alike on this controversial and hardly discussed topic of organ and voice. There is no literature, no research, and no interest in it. Somehow, both the organbuilder and the organist have survived for centuries, performing a musical function which they know little about, but succeeding with such beautiful results that the church continues to use them. Not knowing how the organ world would dictate the design of an organ for the human voice, builders have either ignored or discounted such needs but still produced instruments, which, in many cases, achieved outstanding success. Serendipity perhaps, but the complete description of this remains unclear and unsettled.
Substitutes for the pipe organ have appeared and are used in some churches. In many churches, the pipe organ remains firmly situated because of its success at supporting, accompanying, and leading the human voice to sing. It will continue to do so as long as it performs this task better than any other instrument. It will lose this position when it ignores or is ignorant of its prime role in the church.