Absorption coefficient - Ratio of sound absorbing effectiveness, at a specific frequency, of a unit area of acoustical absorbent to a unit area of perfectly absorptive material. The portion of energy absorbed when a sound wave strikes a material. The absorption coefficient of a material is dependent on the frequency of the sound wave.

The opposite of reflection. Sound absorption results from the conversion of sound energy into another form, usually heat or motion, when passing through an acoustical medium. When a sound wave encounters resistance, absorption occurs. Absorption is measured in sabins (after Wallace Clement Sabine). One sabin is the amount of absorption offered by one square foot of open air

@Brien Holcombe, kmetal Boswell, pcrecord, audiokid , ... and anyone else who may be interested:
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Hi Guys,
RatRig Hardware is a DIY Hardware company based in Europe - Portugal. We develop and sell various Audio and Video related DIY Hardware kits. http://www.ratrig.com

Our first Audio Related kits are Acoustic Panels and Bass Traps for studios, check them out here:

Hello all,
I lost my links many moons ago. Where are you guys getting your OC703/705 Rockwool and Guilford of Maine cloth? I think it's high time to make some corner traps, and the place I used to buy from had a really long dotcomtypename... :) and I've only got two 2" x 2'x 4' panels in the garage and no cloth.

Rod, Space, et al :

I'm researching absorption coefficients on OC 703 and 701.

According to Bob Gold's Chart, 703 2" (plain) mounted flush to wall has the following properties:

125 250 500 1k 2k 4k NRC
0.17 0.86 1.14 1.07 1.02 0.98 1.00

Looking to acoustic treat my room. I want to get safe, non toxic acoustic treatment that still has good sound absorption. Looking for the material wise, since different pieces would be used for different frequencies. Want it safe to breath (even if not covered by fabric), also safe in case my dog accidently chews and swallows some. Also safe to handle.

Built these after doing a lot of research on them, and finally am nearing completion! There will be six total, and I also built stands so that I can make a sort of 'booth' in my room for recording to cut out all of the horrible reflections. Will do some tests once I have them all completed and fitted into their stands, it should be a significant improvement over the space I have now.

For wireless microphones, the loss that occurs when a transmitted signal passes through a material that absorbs a portion of the RF energy, reducing the signal level available to the receiver.

In acoustics, the property exhibited by certain materials to absorb (as opposed to reflect) sound waves. Used by studio designers to control the sound energy in a given space.
Also used in reference to the conversion of sound or radio frequency (RF) energy into heat.