by Tim Adams
We have all likely heard the term acoustics and at once have images of recording studios and sanctuaries covered in acoustical paneling. Musicians will have a love/hate relationship with acoustical treatment as it messes with the natural sound of a space, which can be quite lovely from a performer’s standpoint. However, from a listener’s perspective, natural reverb can be an obstacle to hearing clearly and thus, understanding the spoken word.
There are many different approaches to what is appropriate acoustics for a given space and there is no one answer that will work in every space. There is one question that you will find is present in just about every conversation about the acoustics in a space-do you want to hear clearly or do you want to have the natural reverb? You see, these two goals can be mutually exclusive when it comes to the acoustics in a space.
You can completely deaden the room with massive amounts of absorption, any thus kill the natural sound of the room. This is the goal with most recording studios because engineers want the maximum amount of control over how the final sound will sound.
However, there are other cases where the natural acoustics of a room become quite appealing. For example, most of the score for the “Lord of the Rings” trilogy of films was recorded at Watford Town Hall in England. Also recorded in this venue were the scores of “Sound of Music” and “Star Wars.” Why? Because of the natural acoustics in the space deliver a sound unlike any other, that’s why.
Before tackling what acoustical treatment options are available, it’s important to understand that acoustical planning is not an easy process and you should seriously look at hiring an acoustical consultant to evaluate your space and make recommendations, particularly when you are planning a sound system upgrade. Acoustics can have a massive impact on your sound and there are so many variables involved in deciding what is appropriate for your church and what isn’t. While you can tackle acoustical treatment on your own, you will likely throw money at the wall (quite literally!) and still end up hiring a professional.
Acoustics can have a massive impact on your sound and there are so many variables involved in deciding what is appropriate for your church and what isn’t.
Acoustical Treatment Options
To best understand acoustical treatment, you need to understand the difference between absorption and diffusion. The first absorbs sound while the second deflects sound in many different directions, which can have a similar effect as absorption.
Absorption
These solutions rely on some kind of foam or other fairly dense material of varying thicknesses to absorb specific ranges of frequencies to help control and eliminate sound bouncing off of hard surfaces and creating havoc in the acoustical space. This also has the effect of quieting the overall volume in a room, given enough of these panels are installed, which could be undesirable as that requires your speaker system to work that much harder.
All materials have a resonant frequency; a frequency at which the material begins to vibrate and this can lead to undesired effects. Think of a wine glass shattering randomly when introduced to a resonant frequency and you get the idea.
If you think about sound waves, lower frequencies are much, much longer than higher frequencies and thus they retain their “energy” for much farther distances. This is why you can hear a car with a powerful subwoofer installed coming long before you can see the car; the low frequency sound waves are more efficient in their use of energy. Higher frequencies is generally where you will see most hearing damage and can more easily be defeated with absorption methods. Of course, the more energy you throw at your audience from the speaker system, the more absorption will be necessary to counteract the negative impacts of sound energy bouncing off of walls, floors, and the ceiling.
Generally, low frequencies like corners and acoustical experts can work wonders by using specialty acoustical products called “bass traps,” designed to sit into 90° corners and absorb those pesky bass frequencies.
You also have ceiling clouds, acoustical panels designed to mount to a ceiling and absorb sound bouncing off of those surfaces. Mostly used in rooms with high ceilings, where the increased travel distances involved in sound waves traveling from speakers to ceilings to ears can lead to “echo” type issues if not handled properly.
Diffusers
Unlike absorption solutions, diffusers do not quiet a room, but utilize the concept of reflecting sound to our advantage by providing many different directions for the sound to travel, thus “diffusing” and spreading out the sound energy such that it dissipates quickly. Much like a diffused lighting fixture, the energy is spread out over such a wide area that it “softens” the light into something desirable and appealing.
Diffuser panels can take quite interesting shapes and designs; some of the most common I have seen are small wooden columns of varying lengths extending away from a base, looking much like a complicated cityscape or a 3D waveform. They can become quite visually appealing artistic pieces. More recently, I have seen people experiment with different materials, including 3D printing, which could provide some cost savings if you have the time and materials to try it out for yourself.
Tim Adams spent over 20 years volunteering in church technical ministry and now focuses on helping small churches achieve technical excellence through equipment upgrades, training, sharing best practices and teaching leadership how to cast God-sized vision.
