[Trombone-l] Soundproofing a room

Chris Tune crtune at adelphia.net
Wed Nov 23 17:31:09 CST 2005

The widgets that look like upside down models of a city (with all the little 
buildings at different heights and so forth) are actually diffusers.  The 
heights of the different little raised geometric surfaces are mathematically 
calculated to cause a diffraction effect at particular frequencies.  There 
could be a variety of frequencies that are needing diffusion.  This makes 
the reflections that still occur, less off-putting and more "smooth" in 
feel. There is a lot to this aspect of tuning a room (see next para.).

The standard issue textbook on these kinds of diffractors is the book by F. 
Alton Everest called "The Master Handbook of Acoutics".  This kind of 
diffusor is called a Schroeder Diffuser.  (or may be an enhancment of the 
original Schroeder diffuser effect). This effect is similar to a diffraction 
grating.  Everest mentions a butterfly wing.  The wing looks tan at a 
distance, but when examined under a microscope it has ridges and grooves 
which, when hit with white light, produce a color effect. This has to do 
with the wavelength of the color and the size of the grooves and ridges. 
Diffusion is not the same as energy reduction.  Rather, it is like a 
randomizer of the energy.

Anyway. . .I second the notion of looking into stuff from Auralex.  They 
have a kind of portable "gobo" like wall that can be locked together and 
which should, when added to other measures, be able to reduce sound output 
energy once the sound passes by the barrier.   The more measures you take 
the better.  It would be much better to put up two, half-inch thick fluffy 
wall treatments than only ONE, one-inch thick treatment.  Remember the 
interface between the air and the isolation material is part of the 
reduction in sound energy.  Three treatments would be even better than two.


----- Original Message ----- 
From: "Daryl Burch" <darylburch at speakeasy.net>
To: "List Trombone" <trombone-l at server5.samford.edu>
Sent: Wednesday, November 23, 2005 11:56 AM
Subject: Re: [Trombone-l] Soundproofing a room

> In high school I worked at a truck stop diner as a short order cook. Over 
> the course of a month I saved every egg carton tray I could (that wasn't 
> too covered in gunk) for just such purpose. Imagine the amount of eggs a 
> diner goes through in a day. It adds up quick.
> Anyway, yes it does work. But if you befriend some hapless schmoe working 
> a diner, I strongly recommend lettin' 'em air out for a few weeks. 
> Otherwise, you'll never get any practicing in, you'll become an insomniac 
> AND you'll put on about 50#'s. Because as soon as you sit down with the 
> horn, you'll find yourself drawn almost-zombi-like to your nearest waffle 
> shack where you'll have an 4-egg Denver omelette, a half a pound a bacon 
> or sausage (links or patties) with a full pot o' "road dope"--coffee so 
> thick an' black it'll keep you awake for 6 or 7 states... Then you'll 
> stumble home and spend the rest of the day watching Springer reruns.
> Or at least that's how I spent the summer of '89. But I digress.
> Kidding aside....
> I've seen the egg cartons & hi-density foam (Auralex) baffles in some of 
> the dank&stanky rehearsal spaces I frequent in SF. Mainly they provide 
> deflection points for the sound to bounce off of, and also absorption. 
> Thick, heavy drapes--like the weight of a stage curtain--can do alot to 
> dampen sound, too.
> In the Dolby5.1 studio at 'Xpression in Emeryville (A/V college), the 
> studio is built so that no two walls directly face each other and are 
> covered with dampening baffles. The ceiling has extra dense foam blocks 
> that look like an upside model of a city--all to provide deflection points 
> thereby defusing echo and dicipating the sound waves.
> The bigger music supplier sites (Music123, SamAsh, etc.) have "acoustical 
> treatment" sections on their sites. Or your local Guitar Ctr.
> I had a friend in Cinti, that built his studio in his basement and filled 
> the walls with sand. As much as this sounds like a good idea, you better 
> own the house you do it to.
> So you don't have to fall prey to the diner addiction completely. 
> ......if you don't want to.
> Sorry to ramble. Apparently I still had some remnants of that last pot o' 
> road dope left.
> -D-
> www.radionoise.com
> On Nov 23, 2005, at 11:26 AM, BJMCHAFFIE at aol.com wrote:
>> Adrian, you are correcy on the Egg carton thing.  A restaurant in 
>> Monticello
>> Indiana, known as the Beaver Dam, had noise problems and stapled egg 
>> cartons
>> to the ceiling and walls and the noise was cut by at least half.
>> beldon wade
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