Church Acoustics

Churches require two types of acoustical management. First, we must manage the spoken word and second, the music. Most of the time the spoken word is electronically reinforced through a PA system. Some of the time the music goes through that sound reinforcement system, sometimes it does not. With churches, it is always a balancing act between “music intelligibility” and speech intelligibility. We must hear the spoken word of God and then sing or play music to reinforce that spoken word by communicating through music. The main focus of the Kodiak church was both music and speech.

Our voice, hearing, and language system are designed to be used with both direct and reflected energy. Direct energy is the energy that travels in a straight line from the source such as human speaking or speaker playing music. Reflected energy or room sound is the sound the room produces from the accumulated reflections from its walls, floor, and ceiling. Direct sound does not have any room sound. Reflected energy off of room surfaces helps us tell how large the room is, but does not help us hear what is spoken. In fact, the accumulated reflections are such an issue for speech and music that there is an acoustical measurement called Rt-60 to quantify their interference.

The Calvary Chapel in Kodiak had high Rt-60 times and low speech intelligibility. We had to turn that ratio around. To do that, you treat the source of the problem; the wall and ceiling surfaces. With speech intelligibility issues, you must treat with absorption technology but not just any type. You must be choose the correct rate and level of absorption, since you have to cover such large surface areas with the technology You must calculate how much square footage of material to use, of what rate and level, and where does it go within the room. Not all sound absorption technologies will work for both music and speech.

Red Zone

The red group are rooms that produce so many low, middle, and high frequency energy issues, that large amounts of absorption treatments are required. There is not enough space for diffusion in terms of surface area or distance for wave lengths to fully form. It is the room sizes that are below 2,000 cu. ft. in total volume. The large amounts of treatment surface area, especially in the lower frequencies, will take up so much space that you might not be able to work in it.

Yellow Zone

The second group (yellow) of room sizes is from 2,000 – 4,000 cu. ft. This group of room sizes and volumes has the necessary space to allow for enough low, middle, and high frequency absorption along with enough space for diffusion. You have the space to place the appropriate low frequency absorption technologies and enough distance for diffusion to work. You will still have issues, especially in the low end but they can be predicted and managed.

Green Zone

The third group (green) is greater than 4,000 cu. ft. It is an ideal grouping of width, height, and length to allow for almost any usage. These rooms have enough distance to allow for appropriate management of all reflection time signatures, unwanted modal pressures, along with enough distances to allow for diffusion to do its job correctly and allow for all diffused wave forms to fully form.