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What's "Acoustics"?

Blake Engel, All Church Sound

This short article wil help you understand what acoustics is, what affects it, and why it's even important to churches.

Acoustics is the science of sound. It involves the laws of physics that determine how sound is produced, how sound waves act, and how they behave in different settings. You've probably said (or heard people say) a room has "good acoustics" or "the acoustics were terrible!" Acoustics describes the way a room sounds or what a specific room does to sounds produced in it. Every room has differnt acoustics. There are three major variables that determine a room's acoustics. Size, shape, and the materials used to finish the space. In fact, its been said a room's acoustic signature is based as follows: 60% size, 30% shape, and only 10% the finishing materials. Other studies have shown that the construction methods have a lot to do with the acoustic properties of a room, too. Two identical listening rooms were built--one room had wall studs spaced on 16-inch centers and many small conduits, the other room was built with studs on 24-inch centers and fewer large conduits. Random people were taken off the street and listened to music played back in each room. Almost every person said room "A" sounded better than room "B". (The previous example was written from memory as no suitable white papers were found that spoke of this test.) This proves that even the things hidden in building construction have an effect on the acoustics of the room. What must be stated now is that there's no set of laws that describe how a room should be acoustically. That is, depending on the usage of the room, different acoustics will be used. For example, a college classroom will need to have acoustics best suited for speech--the acoustics must render the speech clear and not overly reverberant. On the other hand, a cathedral with a pipe organ may require very reverberant acoustics. If a piano was played in that space, it would sound very muddy though. It's not an easy task to predict what the acoustics of a room will be like before it's built. General statements can be made, however, based on the construction and materials used. A flat concrete wall will reflect the sound, a wood wall will tend to vibrate (based on what it's made of and how it's attached to the wall studs). A concave wall will focus sound, while a convex wall will disperse sound. Heavy drapes on a wall (like a movie theater) will absorb sound. Carpet on the main floor may help keep the sound of people moving down, but it can be a damaging factor to a choir loft. Other factors include the temperature and humidity in a room, the number of people in the room--all of these factors must be taken into account. A short note--if a church (for example) has a platform or stage area separate from the rest of the congregational seating (much like a theater), the acoustics on stage will be different than in the seating area. This affects the way a group of performers can work together--something often overlooked. We've known about acoustics for quite some time now. The Greeks and Romans used the laws to their benefit. Monks spent months tuning rooms by filling the pillers with sand or by letting the sand out. Too many times the acoustics of a space is ignored. No thought is put into it, and the result is often disasterous. Churches have been built this way--and now they are closed because no one could hear the message clearly, so they left the church. No one was there to fund a "fix-it" plan, and so the church had to close its doors. There have been times when the natural stone walls have been painted for only a few hundred dollars--only to be sandblasted clean for tens of thousands of dollars because of how the paint ruined the acoustics of the space. How can you know if what you're doing is going to be good or bad? How can you know what the final outcome will be? The answer is easy--hire an acoustical expert. These people spend their lives learning and applying the laws of physics to rooms. They will often guarantee the acoustics of your room--what architect or lay-person will do that for you? If you'd like to learn more about acoustics, look it up in an encyclopedia. You'll be amazed at the wealth of information there. If you want to know how acoustics applies in churches, get a copy of the book, "Why Are Church Sound Systems & Church Acoustics So Confusing?" This book will give you a set of rules you can build by. If you follow all of the rules, your room will turn out great. If you don't follow the rules...well, who knows what you'll get! Remember, a law is a law--you can't bend it to make it fit, you can only abide by it or break it.