Date:         Wed, 20 May 2009 12:36:06 -0400
Reply-To:     David Beierl <dbeierl@ATTGLOBAL.NET>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         David Beierl <dbeierl@ATTGLOBAL.NET>
Subject:      Re: Sound Deadening...here we go :)
Comments: To: Jeff Lincoln <magikvw@GMAIL.COM>
In-Reply-To:  <c803c1a70905200857n193c63d2ge055d6873af987ab@mail.gmail.co m>
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At 11:57 AM 5/20/2009, Jeff Lincoln wrote:
>So, any "poor mans" materials anyone can suggest? Also, it makes sense that

Red Green did it with egg cartons as I recall... </tongue-in-cheek>

Just a general thought -- you have four things to deal with as I see
it: transmission into the space, absorption of sound already inside,
panel resonance and logarithmic response.  For absorption you want
fluffy stuff that will trap the sound and waste it as heat.  For
transmission you want alternating layers of dense and less dense
non-resonant material -- the Navy used to (still does?) use R-A-L --
3/4" of non-bouncy rubber loaded with small flat voids and flakes of
lead.  Transmission in particular benefits from full coverage.

Vibrating panels can generate a lot of noise.  They can be damped and
have their resonant frequency lowered by comparatively small patches
of mastic stuck to one side.

Logarithmic response is the killer -- every time you get rid of 90%
of the sound energy, your ear perceives it as half as loud as before,
recursively.


  --
David Beierl - Providence RI USA -- http://pws.prserv.net/synergy/Vanagon/
'89 Po' White Star "Scamp"