insulation coefficients

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stuckatwork

insulation coefficients

Post by stuckatwork »

Hey,
I have a qusetion about sound absorption coefficients. I'm looking at the Owens Corning site and I see some of the coefficients are over 1.00:

http://www.owenscorning.com/comminsul/d ... Series.pdf

It is my understanding that a coefficient of 1.00 would be 100% absorption of a particular frequency. Some of the coefficients, such as the plain 703 @ 500hz is 1.14. Maybe I don't have a very good understanding of what these coefficients mean but can someone please explain to me how a material can absorb 114% of a frequency?

Thanks,
Jon
John Sayers
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Post by John Sayers »

Jon - I've seen this answered somewhere, maybe by Eric at Yahoo. I remember it had something to do with Edge effects or sumthin. :)

Sorry I can't answer it further.

cheers
john
Ethan Winer
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Re: insulation coefficients

Post by Ethan Winer »

Jon,

> can someone please explain to me how a material can absorb 114% of a frequency? <

As John said it's due primarily to edge effects. And those can seriously skew the results! I just wrote a very detailed description of this exact issue as a new sidebar for my Acoustics FAQ, here:

www.recording.org/users/acoustics

This sidebar, "The Numbers Game," is at the very end, or just click it in the table of contents at the top of the page.

--Ethan
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