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two channel listening room acoustics 9

The answer to the question do acoustic panels work can be answered by identifying the problem you wish to treat and using the correct technology to treat the issue of concern. Not all products are created for every issue and there is no one size fits all as most companies claim. Nothing could be further from the truth. Every acoustical issue within our rooms has an identifying marker and name. It is called frequency and each frequency is expressed in a unit of measure called a hertz. (Hz). Do acoustic panels work? Yes, if you match the acoustic panel to the appropriate frequency and amplitude issue. Each panel has a frequency range that it works at and this frequency range must match the frequency range of the acoustical issue. Let’s examine some of the usages for acoustic panels and identify the problem and then describe the solution. Through this process we will find the answer to do acoustic panels work.

Activated Carbon Diaphragmatic Absorber image

Energy within our rooms is broken down into two main groups. We have low frequency or “bass’ issues. We have all heard this problem. People say too much bass, turn it down. There is too much low frequency energy within the room itself. The room can not hold certain frequencies due to the wavelength and the room dimensions not matching with each other. Low frequency energy within our rooms is all energy that falls below 100 Hz. Middle and high frequencies are above 100 Hz. and extend through 20,000 Hz.Low frequency energy is like the ocean waves. It rolls through our rooms at certain time intervals and keeps oscillating through the width, length, and height of our rooms Middle and high frequency issues are more like sunshine. They are shorter and thinner and move in straight lines.. They do not oscillate through our rooms like waves or low-frequencies. Low frequency energy, waves, requires one panel type to treat. Middle and high frequency energy require a completely different panel type.

Low-frequency energy is best absorbed using the most efficient method possible. You must be able to grab a hold of low frequencies and attenuate them enough so they don’t create more problems to begin with but then also minimize the existing issues. At Acoustic Fields, we offer a DIY series of product builds. Here is an example in the video of building a diaphragmatic absorber. Watch the video process. .The most powerful low-frequency absorption process is called diaphragmatic absorption. When we look at low-frequency, we must use diaphragmatic absorption like a speaker without power. The diaphragm vibrates in sympathy to the pressure placed upon it by any low-frequency device such as a subwoofer. The diaphragm slows the low-frequency pressure wave down before it enters the cabinet where our carbon technology is located. When the pressure wave gets inside the cabinet it quickly realizes that the atmospheric pressure is much less inside the cabinet than the outside air pressure in which it was created. When it “sees” this lower pressure area it collapses and we have attenuation or absorption occurring. A diaphragmatic absorber works on sound pressure so if you need to know do acoustic panels work, always choose diaphragmatic absorption and you won’t have to address this issue again within your room.

Image of Acoustic Foam sheets

Diaphragmatic absorption works well for low-frequency energy but what about the rays of energy or the middle and high frequencies. We can use diaphragmatic absorption for this energy type. We must use technology that works on air flow, not pressure waves. One of the most economical and common of these treatment types is open celled acoustic foam. Foams come in two flavors. We have open celled foam and closed cell foam. Closed cell foam is the foam they put in seats in our cars and sofas. It is designed to support weight with its closed cell structure. Open celled foam has open cells where air containing sound enters and is bounced around inside each cell. This movement produces friction and friction produces heat. Once we have changed the airborne energy to heat, we have absorption occurring. We are creating or destroying energy. We are changing its form into heat and this energy transformation produces absorption. Be cautious. Not all open celled foam is created equal. You must use the proper rates and levels of absorption when you are dealing with music and voice.

Acoustic Fields Foam Panel Technology in Studio
Acoustic Fields Foam Panel Technology

Music and voice are different from noise technologies. Noise technologies seek to absorb as much energy per square feet as they can. With music and voice we want to absorb just enough energy across the frequency range to better manage the energy amount, position, and frequency. Music and voice require special rates and levels of absorption. Music and voice are special and we must not over absorb the voice so the room sounds too dead. We also must absorb enough to lower the reverberation times within the room so we have more speech intelligibility or we hear more words in every sentence. Hearing all the dialog through car crashes and explosions in our home theaters is highly desirable. In order to achieve both low-frequency resolution and detail with dialogue resolution and detail we must use two separate and distinct technologies.

Dennis Foley

I am an acoustic engineer with over 30 years’ experience in the business. My technology has been used in Electric Lady Land Studios, Sony Music of New York, Cello Music and Films founded by Mark Levinson, and Saltmines Studios in Mesa, Arizona, along with hundreds of others.

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