Lately, an increasing number of people (particularly those among the younger set) seem to seek digital signal processing solutions to achieve higher quality church sound before attempting other methods. These days, I frequently find myself rolling my eyes when I see questions in social media to the effect of “what plug-in will make the sound clearer in my Sunday morning worship mix?” I don’t mean any ill will. Unfortunately, there’s no Magical Clarifier XL2000 plug-in that can resolve the acoustical challenges posed by the spaces in which we ply our trade — at least not yet. The clarification being sought can only result from acoustical solutions, and many of those solutions are not simple, nor will one single “fix” resolve all the problems. However, there are some relatively easy solutions that can be implemented at a reasonable cost and without completely redesigning our sanctuary space.
R&R: Reflections and Reverberation
The biggest enemies of clear, distinct sound in the church are reflections and reverberation. A certain amount of ambience is desirable, but it’s preferable to have some control over how much. The chaotic soup of too much acoustical reverb is caused by reflective surfaces — usually hard, flat surfaces that bounce sound energy around the room. The best way to get these reflections under control is to either absorb them or to break them up. Parallel reflective surfaces are our worst foe — they create the nastiest of all reflections — the dreaded flutter echo — it’s that “boingy” sound you hear when you clap your hands in an empty room with no furniture. But even if the reflective surfaces are not parallel, sound will bounce around between them until its energy decays away, and we still have a cacophonous soup. So how do we diminish it?
Without delving deeply into acoustical physics, we all know intuitively that hard things tend to reflect sound, and soft, squishy things tend to swallow sound. So the obvious thing to do is to cover the hard, flat surfaces with stuff that’s softer and squishier (yes, I am going to go with that technical term). Using materials like cloth to cover reflective surfaces will help, but that notion must be qualified. Hanging bed sheets in front of drywall surfaces won’t help much. Something more like a heavy comforter (which has a higher squishiness coefficient than a bed sheet) will be more effective. But we can’t just hang comforters up — the aesthetics simply won’t do. Drapes are a plausible solution, and the heavier and thicker the better. Movie theaters, which are traditionally box-shaped with parallel walls, have leveraged large drapes since time immemorial to tame reflections (uually in some shade of maroon or navy blue). In particular, windows (which are very hard and flat) are strong candidates for heavy drapery, but those same drapes can be extended to cover substantial swaths of wall surface too. Side walls can benefit greatly from this solution.
The rear wall of the sanctuary space is of particular concern. Most of the time, our main front of house speakers will be oriented in such a way as to direct a lot of energy toward that back wall, and the result is a substantial single reflection that arrives at the ears of our congregation a brief moment after it initially emanated from our speakers. This slap echo both contributes to the overall reverberance of the space and also interacts with the direct sound in a way that causes a phase incoherency that further reduces the clarity of our sound. Any reduction in the amplitude of that echo will help, and our aforementioned drapes can contribute to an increase in clarity. The rear wall is unlikely to be the only problem we face by way of reflection, however. It makes sense to take a stroll around the space and visually search for large, flat surfaces that will reflect sound. They’re not always around us like walls. Balconies and hard, flat ceilings cause trouble too.
Drapes can be a quick, easy-to-implement solution, yet acoustical panels are another fairly simple solution that won’t necessarily break the bank. There are reasonably-priced panels available for purchase, and they’re not hard to install. Since creating a large, flat, absorptive construct is not complex, it’s also plausible to design your own, and via assembly-line volunteerism, manufacture as many as you want at relatively low cost. Rockwool and compressed Fiberglas serve well for this purpose, and can be nicely corralled in a wood frame, covered with cloth, and positioned in the places in our room where big reflections emanate. Panels of varying sizes and even shapes can be constructed to approximate the surfaces they’re intended to cover. If you’re thinking aesthetically, the cloth covering the panels can be in colors of your choosing, and could even feature images. In the case of parallel surfaces, we don’t necessarily need panels facing each other — just one that will swallow the reflection from the surface directly opposite of it. One application of this is the sanctuary’s side walls. If they’re indeed parallel, the absorptive panels can be staggered in such a way that there’s one on each side absorbing reflections from the other side. Tidying up reflections coming from behind our musicians at the rear of the platform is also tailor-made for absorptive panels or drapes, and this can make a nice contribution to the overall control of the space.
An alternative to absorption is diffusion, in which reflections are not just swallowed up but broken apart and sent in numerous directions. The physics here are a bit more complex, but replacing one big reflection from the rear wall with lots and lots of smaller reflections moving in many directions helps drastically reduce that unpleasant phase interaction we get when the FOH energy meets itself coming and going in the middle of the room. Diffusers can be deployed in places other than the rear wall, helping to maintain some scattered reverberance if it is desired. Diffusers are generally more expensive to construct, the result of which is that purchasing them outright is more likely than with absorptive panels. Nevertheless, they still fall into the category of “easy” fixes.
Note: After making any changes to the acoustics of the room (even if they’re minor), it’s a good idea to re-tune the P.A. system once the acoustical adjustments are complete. Even if the re-tuning amounts to only micro-tweaks, we still want to maximize the improvements that our new acoustical adjustments are intended to accomplish, and touching up the spectral energy disbursement of our system, among other things, is definitely desirable.
Non-Acoustical Fixes
A list of acoustical fixes should certainly include easy fixes in the way the audio system interacts in the acoustical space. Some of these potential solutions don’t pertain to actual room acoustics, but will help improve the interaction of our system in its space. Ensure the P.A. speakers are located and positioned properly. It’s generally not a good idea to jam our FOH speakers right up against walls, or the ceiling or the floor, for that matter. Probably even more important than that is to ensure the speakers are directing as much energy as possible toward the congregation and as little as possible toward reflective surfaces. This simple fix can have a profound impact. Also, try to reduce or eliminate stage volume, which contributes to the cacophony. Isolating drums is likely the highest priority here, and the elimination of speakers on the platform (guitar amps, floor wedges, etc.) will help. If your guitarists aren’t sold on the amazing modeling technology now available, they can tuck their amp/mic pairs backstage or into an isolation cabinet.
Another obvious easy solution is to reduce artificial reverb. Too much of the “480 Hall” fader is a common rookie (volunteer) mixer mistake. And while at the mixer, consider turning the master fader down a touch — more SPL equals more reflections. Another idea worthy of consideration: As human bodies are fairly effective absorbers of sound energy, don’t offer five services with 100 congregants occupying only 20 percent of your 500-seat room. Maybe two services with 250 congregants each or one service with standing room only. That’s definitely an outside-the-box idea, but it has some merit.
By combining a few of these ideas, a church should be able to accomplish noticeable improvements in the acoustical performance of its space. Try putting a few of these into practice!
John McJunkin is the chief engineer and staff producer in the studio at Grand Canyon University.
