Kodiak, Alaska, USA
To Your Room
Buildings are all about size, volume, and usage. What are the dimensions, what is the total volume, and what its usage? All of these three variables must be addressed. It does not matter to the room what you do in it. It will tell you if you are cooperating with its size and volume for your usage or if you are exceeding the rooms’ acoustical limits. The members of the Calvary Chapel in Kodiak decided to listen to their room more closely.
Speech Intelligibility of the Spoken Word
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.
Rt-60 times Were Too High
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.
We ran the numbers from our data base and sent the church our foam technology. They built the panels to put the foam in and did the installation per our design (Click here for more information).We told them how many units they would need and where to place them. They were able to use our DIY acoustic panel and build the cabinet, secure the foam, and place the fabric across the face of the unit. They followed our design and build procedure accurately. The finished units looked professionally built and installed. I will let Ryan, the project director, tell you how they sound.
Acoustic Foam Absorption Performance Chart
- Acoustic Fields Absorption Coefficient in %
- Auralex Absorption Coefficient in %
- Sonex Absorption Coefficient in %
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.
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.
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.
DIY Acoustic Foam Panels
With our DIY Acoustic Panels you will have a functioning piece of acoustical furniture for your home theater, personal listening room, or professional recording studio. You will have a foam cabinet that will house your sound absorbing needs but will also add to the overall well balanced look of your studio or listening room. You will be able to create a piece of furniture that has a real wood stain to match the wood stain and finish on your speakers. You will enjoy a foam cabinet that has the correct absorption rate and level for your particular rooms needs and not some generic, one size fits all box, which never will.
The DIY acoustic panels are full build drawings for any acoustical foam to be inserted inside the box. The foam of your choice goes into the box and an acoustically transparent fabric goes across the face. Acoustic Fields can provide you with foam pre-cut to fit your box and the acoustically transparent fabric which is available in over 38 different colors.
We have three thicknesses you can choose from depending on your sound absorption requirements. Our foams go from 125 Hz. – 7,500 Hz.