Noise abatement for a rack

[Jim Lux]

Hie thee to a library or bookstore and get a book on audio recording studio 
design (there are a bunch aimed at amateur/garage type operations).  They 
have a lot of very useful and practical information on noise reduction, 
which is truly an art.

Two things to worry about:
conducted through a solid object - panels, racks, etc - and then reradiated 
via a panel, etc. - mass and soft help (lead, sand, etc. -- rigid is bad)
conducted through the air - through ducts, etc. - torturous path (length 
attenuates), acoustically dead (soft, massy) and nonreflective.

You need to know a bit about the spectral characteristics of your noise.. 
LF is a different problem with different solutions than HF.  Maybe a 
microphone on a laptop and one of the freeware spectrogram progams?  You're 
not looking for quantitative analysis to the nearest 0.001 dB here... just 
a general guide to where the problem is...


At 10:34 AM 12/4/2002 -0800, you wrote:
>Anybody here ever try noise insulating a rack???
>
>I have to share a room with our new 20 node cluster
>and it would be nice to be able to do so without having
>to wear earplugs all the time.  The 20 2U single Athlon
>systems are mounted in an open frame 4 post rack.  Using a
>Radio Shack sound level meter (catalog #33-2055) set to
>dBA, fast weighting the following values were obtained
>for (front,left side, back, right side):