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If A Tree Falls In The Forest...

The Presence Of A Human Factor On Church Projects Leads To Difficult Questions

(originally published in the January 2000 issue of Systems Contractor News)
Reprinted with permission from Kurt Graffy & Systems Contractor News

Welcome back from the preceding thousand years! Was the millennium good to you? How about those overrated Y2K prophecies? Well here we are in January, and here it is, the January edition of SCN, just like any other year...nevermind that this is the January 2003 edition!

Okay, okay, so meeting the deadlines for publication may result in one writing the column before the event, and missing the big story, sort of like the Dewey/Truman prediction fiasco (for you students of journalism or American history). Consequently the safest thing is to write about something rather immutable, which also happens to lead right into this month's diatribe.

One of the things that has always amazed me is the famous (or infamous) "general knowledge" regarding churches and sound systems. This general knowledge states that churches typically will have three or four sound systems over the years before they finally get a system that's right. Of course one's first thoughts are "What a boon for the manufacturers, a potential market four times larger than the 'installed base'!" Also what a bonus for designers and integrators "work" that trickle-down economy! But perhaps the real nagging question is "Why?"

The old adage has it that you should never bring up sex, religion, or politics in a conversation, but is ironic that along with the obvious factor, another of these topics (your call as to which one) is so often a part of church projects. Because the interest in a new audio system is presumably based upon dissatisfaction with the current situation, one would think there would not be such an insistence on "holding on" to the very factors that have resulted in the current displeasure. But the politics of the environment often work against common sense. There are relationships involved which are much thicker than science. How many times have you discovered that a career installing loudspeakers in automobiles has apparently rendered someone's cousin knowledgeable in the full aspects of acoustics and audio systems?

On the other hand, I continue to be impressed at the deep-rooted faith of many pastors, church committees, and their architects that the Lord has chosen to suspend the laws of physics from operating within their sanctuary. How else can one explain the often adamant stance that nothing shall be seen, nor shall it be larger than "(fill in the blank with a ridiculous size which varies with the project, typically in an inverse rela-tionship with the reverberation time!)." However as far as I know neither a local repeal of the laws of physics nor an aural miracle have much chance of occurrence.

And of course this discussion wouldn't be complete without the apocryphal story of the "church just like ours which used XYZ and it worked beautifully," where XYZ is a system, location, device, size, color which makes absolutely no engineering sense in this project environment. (Just kidding about the color.) Naturally a visit to the ref-erenced system and church always brings to light an element which was completely forgotten. Yes they only had one loudspeaker for the entire church, but there were only 50 people, or the T60 was under a second or you know the way it always turns out.

So where does that leave us? Hopefully, along with our justified frustrations, somewhat humbled, with an understanding that the sense of personal involvement and ownership runs deep within church environ-ments. Consequently it is not merely the acoustic challenge which must be met, but a human one as well.

How to tell the enthusiastic volunteer that the many hours of work they have cheerfully donated to the church audio system are worthless? How to tell someone who is interested and well-meaning that they are irrevocably incorrect, and their past advice has led to the purchase of expensive equipment which although excellent, is completely inappropriate for the intended usage? How to take these people that you have es-sentially held up to ridicule and insult and make them part of your team, helping them to understand the engineering behind your recommendations (removing it from the realm of personal opinion), and bringing them into agreement and buy-in with the system design and concepts?

Speaking from experience, you ignore this aspect at your peril! Regardless of how well your system works, if you do not or cannot solve the human challenges of the situation, your system will become one of the transitory systems along the route to their final installation.

So, speaking of transitory, what if a tree falls in a church without walls or ceiling? Would it generate a reverberant field? How about if the sound system produced energy that was completely incident upon the seating area and none of it intersected the room boundary surfaces? Would it generate a reverberant field?

The answer is that if you fully obey the First Commandment of Audio (Thou shalt put the Sound where the People Are) and minimize the sound energy reflecting off room boundary surfaces, you can effectively reduce the room reverberation which is generated via the sound system.

Why do we care about that pesky reverberation time? One of the banes of church work is the dichotomy between music and speech. From a music standpoint we want the fullness and support of a fully reverber-ant environment, whereas the signal to noise demands of intelligibility require us to emphasize the ratio of direct to reverberant energy. Consequently we add absorption to reduce the reverberation time, we move loudspeakers closer to the listeners to increase the direct energy and minimize the acoustic power energizing the reverberant field, and other variations on the theme--not always to the benefit of the music.

With the advent of new loudspeaker devices with extremely narrow vertical cover-age angles (compliments of amplitude shading and frequency tapering via DSP) the seemingly insurmountable task of serving two masters (and it's Biblical, look it up) appears more possible than ever before. It is not merely theory. We have measured significant reductions in room reverberation time utilizing these phased array devices com-pared to devices with minimal pattern control, The result? Intelligibility goes up via the audio system, while reverberation time for music remains intact.

So what about those laws of physics anyway? Well one of the interesting aspects of our times is the sneaky way new tools turn up which ignore the law you were focused upon, and solve the problem from another direction. As Pete Townshend says, the "trick is to walk in backwards like you're walking out." Got that?

Kurt Graffy (kurt.graffy@arup.com) heads up the San Francisco office of Arup Acoustics, a global acoustical consultancy based in the UK. He is the vice-chair for the Audio Engineering Society’s Technical Committee on Acoustics and Sound Reinforcement, and has been an instructor at various Syn-Aud-Con special seminars.