Grace Church, Wheeling, IL

Grace Church, Wheeling, IL

Sound Systems or Acoustics—Which is more important?

Blake Engel

Take a church sanctuary—any church sanctuary. Fill it with a congregation and have the pastor give a sermon. What does the pastor need more—a sound system or good acoustics? Now, using the same sanctuary and same congregation, have a choir of 40 sing with organ and piano. What’s more important—a sound system or good acoustics? Again, use the same sanctuary and same congregation, but this time add a contemporary worship team (complete with piano, keyboard, drums, guitar, etc.). What’s more important—a sound system or good acoustics?

In each case, both the sound system and acoustics are important. but which is more important. The use of electronic sound systems is quite new, really. It wasn’t until the 1940’s that the use of electronic amplification in churches really began. This was because it was a new, expensive technology, and in the past, no sound amplification was needed (primarily because the number of planes, trains, automobiles and other noise makers was low). Prior to the 1940’s the main concern was acoustics.

Sound behaves differently inside a room than it does outside in an open space. Outside there are no large, flat reflective surfaces, there is no ceiling, and the floor is made up of many different materials. The only two places outside in an open space that come close to a closed room is the Grand Canyon (and other similar rock formations) and bodies of water with a smooth, calm surface. Rock is hard and a great reflector of sound waves, so is water.

When a structure is built, the inside is usually finished with hard, flat surfaces (walls, ceiling, floor). These hard surfaces reflect sound waves. Depending on the characteristics of the surface (its composition, size, shape), different frequencies of sound will be affected differently. For example, a room that has all of its surfaces carpeted will be boomy sounding because the carpet is absorbing the high frequencies sooner than the low frequencies are being absorbed. In such a room, there’s nothing a sound system (pure electronics) can do to overcome the boomy room.

Another example is a room with two flat parallel walls. Sound waves will bounce back and forth between these two walls very rapidly (at the speed of sound), creating an echo that sounds like a ping-pong ball being dropped on a hard surface. Again, there’s nothing a sound system (pure electronics) can do to overcome this echo.

Finally, a third example—an air-conditioned room built with the air conditioner blowers and compressors right outside one of the side walls. The noise created by the equipment will be loud, and, although a sound system may be able to produce sound levels louder than the air conditioning equipment, you’re still stuck with the noise (it hasn’t reduced the noise at all). Installing the air conditioning equipment in a different location or building the wall differently would have been the best solution. You can’t fight an acoustical problem with a sound system!

Depending on the acoustical problem the room has, installation of a sound system may in fact make the problem worse! Although proper design of the sound system shouldn’t produce acoustical problems, in many cases the sound system helps show the acoustical deficiencies. Remember, a sound system increases the volume of a person’s voice or pre-recorded music. A voice un-amplified in a room may sound OK, but when amplified may excite the room to a point that acoustical problems are much more noticeable.

In answer to the question presented, the acoustics of a room are very important, even more so than the sound system itself. A sound system can only amplify sound, it can only perform as well as the acoustics of the room allow it to. A sound system amplifies everything, good and bad. Just like a microscope can only magnify (it can’t show us things that don’t actually exist), a proper sound system can only present a mirror image of the acoustics of the room.

So, before you begin investing the Lord’s money in audio equipment, be sure to take a look at your acoustics—or hire someone to do an acoustical analysis of the room. It may cost a little more in the beginning, but the final product will be well worth the effort and money spent.

Grace Church, Wheeling, IL

Project in Progress (2004)

We were asked to participate in the audio system design and acoustic elements after construction had begun. The slab was in place, and both exterior and interior walls were framed. The HVAC system was in, and the electrical conduit was going in. I met with a church member, David Kim, who was also the manager for the facility and engineering; acting consultant/general manager for the project.

A design for the audio system and acoustical sweetening that could still be done was made. Being late in the project, compromises were made for both the audio system and acoustics. There still exists flutter echoes and other reflective problems, but these may be addressed with panels at a later date. The audio system sounds natural and can certainly fill the room, though the controls are located in a less-than-ideal place.

The room seats just over 500 and is used by width (wider than deep). The floor is sloped and the seating is all theater-style.

See the back wall, above the wood? Those fabric panels are an acoustical feature.

The panels are about 6-inches deep and contain half-rounds which diffuse sound. The original plan was to install wood over the entire back wall; this solution looks great and very few (if any) will ever know it’s an acoustical feature.

The speakers still have aiming adjustments that need to be done. Although there are adjustments needed and some acoustical issues, the audio system can operate stable (no feedback or ringing) with one mic open, miking a person speaking in a normal voice from 40-inches away, with enough volume to fill the room so that all may hear.

The speakers were all installed with a custom all-steel bracket. This couples the bass frequencies into the structure and makes for an easier and cheaper method of installation.

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