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29th December 2010
#1
Gear Maniac

Perforated Panel Absorber Variables

Hi, I'm looking at this tutorial and decided to knock up a quick program to make dialling in the variables easier. More specifically, I'm looking at this equation for absorbers with holes:

Freq = 200 x square root of (P/(D x T))

where:
P = perforation percentage (eg, 5%)
D = depth of air space (in inches)
T = PT + 0.8 x HD
where:
PT = panel thickness (in inches)
HD = hole diameter (in inches)

What would you say would be the upper and lower limits for the variables Freq, P, D, T, PT and HD?
29th December 2010
#2

No need to reinvent the wheel.

Check it out: Porous Absorber Calculator V1.56
29th December 2010
#3
Gear Maniac

Interesting spreadsheet but I couldn't find out how to calculate for perforated panel absorbers (hole size, perforation ratio, etc.). Is it capable of doing this?
29th December 2010
#4

Quote:
Originally Posted by technocolour v2
Interesting spreadsheet but I couldn't find out how to calculate for perforated panel absorbers (hole size, perforation ratio, etc.). Is it capable of doing this?
Absolutely.

Did you realize there are several pages? Each page is devoted to a specific type of absorber: i.e. - porous, perforated panel, and slat.

This calculator is the best on the internet for this application IMHO. It's based on the transfer functions set forth by Trevor Cox and Peter D'Antonio in their joint effort "Acoustic Absorbers and Diffusers: Theory and Application" which I highly recommend if you are serious about designing and building such devices.

Amazon.com: Acoustic Absorbers and Diffusers: Theory, Design and Application (9780415296496): TREVOR COX, Peter D'Antonio: Books

Have fun!

-MM
29th December 2010
#5
Gear Maniac

Awsome! I didn't notice there was more than one page
29th December 2010
#6
Lives for gear

Quote:
Originally Posted by Magickman
This calculator is the best on the internet for this application IMHO. It's based on the transfer functions set forth by Trevor Cox and Peter D'Antonio in their joint effort "Acoustic Absorbers and Diffusers: Theory and Application" which I highly recommend if you are serious about designing and building such devices.

Amazon.com: Acoustic Absorbers and Diffusers: Theory, Design and Application (9780415296496)
The link is to an older 2004 edition of the book, priced at 191 \$US (!!)

There is a newer 2009 edition of the book, priced at 133 \$US, still not cheap.

Amazon.com: Acoustic Absorbers and Diffusers: Theory, Design and Application (9780415471749)

I paid about 95 \$US new from amazon back in February of this year...
29th December 2010
#7
Lives for gear

I'm looking at building some too. Let us know if you do build them and how it turns out!
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