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Sound absorbing foam rubber panels????


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#1 of 7 Derrik Draven

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Posted March 19 2001 - 06:19 AM

Does anyone know what the name of that sound absorbing foam, used in studios and such, is called...or where to get it?

It's usually black, soft foam rubber, looks like a bunch of stalactites are on it??? Kind of like black, foam, egg cartons?

I'm contemplating putting this on the ceiling in the HT room I'm currently designing. They would certainly help lower the sonic boom through the floor upstairs and, I can hide all my wiring underneath the foam rubber material. Not to mention it should help wiping out alot of the audio reflections I have in my basement.

Any help is greatly appreciated!
Better to have a gun and not need it, than to need a gun and not have it.

#2 of 7 Tom Bley

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Posted March 19 2001 - 06:40 AM

Actually, the material won't do anything to lower the sonic boom, you need mass to stop structure born noise transmission. Example, double drywall, isolate the ceiling in your theater from the floor above (essentially a room within a room). There are good construction topics over at www.avscience.com click on home theater construction, also check out www.ASC-soundproof.com

#3 of 7 Deane Johnson

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Posted March 19 2001 - 08:55 AM

Tom's post is right on target and corrects a misunderstanding that many have. Keep in mind, mass stops sound transmission, soft stops it from being reflected.

The stuff you are talking about is awesome for taming the sound bouncing around in a room. It does nothing for booms and lower frequencies wanting to pass through it. At the same time double dry wall provids mass that helps stop sound from passing through it, but does nothing to stop the reflected sound from bouncing around the room.

As Tom pointed out, double drywall is only a partial solution to sonic boom transmission. Sound will hit even double drywall and it will act as a drum head, allowing the vibrations to pass right through the wall studs or floor joists to the next space. Just not quite as much. That's why isolation of the double drywall so that the sound waves can't pass on through helps.

Reflections within a room are pretty easy to deal with. The passage of sound through to another space is much more physically complicated.

Deane



#4 of 7 gregstaten

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Posted March 20 2001 - 04:58 AM

The material you are asking about is called Sonex. It is designed to diffuse sound reflections. As other said, it isn't designed to prevent sound transmission.

-greg


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#5 of 7 Richard Greene

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Posted March 20 2001 - 07:34 AM

Please realize the more sound energy you keep within the listening room, the louder the bass resonances
will be. Flexible walls such as single layer 1/2 inch plasterboard are best for controlling room resonances in ordinary home listening rooms -- concrete is worst.

Some other posts were not correct about the ability to absorb bass energy using foam or fiberglas insulation.
It is actually easy to absorb even deep bass with these materials, but the thickness required makes it impractical
99% of the time. The thickness required is roughly 10% to 20% of the wavelength of the sound involved. For a 100Hz. tone that has an 11 foot wavelength, 1.1 to 2.2 feet thick fiberglas will work well. For 20Hz. these materials are completely impractical, but I mention this because any available space should be filled with fiberglas -- it can only help reduce sound transmission to other rooms.


#6 of 7 ErichH

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Posted March 21 2001 - 05:39 AM

2 walls and an air space does wonders , but you're reducing the sq ft of your room .
Like everybody says - the quick fix is double sheetrock - try 5/8 over 1/2 and
stagger the seams . Framed Owens Corning 703 & 705 works well on the walls and
corners (for high/mid control). You'll get many opinions on how much to use .
The foam looks good (to some) but does very little for either purpose .

Eric


#7 of 7 John Weitner

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Posted July 16 2001 - 03:56 AM

>Like everybody says - the quick fix is double sheetrock - >try 5/8 over 1/2 and stagger the seams .

I want to do this - does anyone advise having an airspace between the 2 sheets and use rubber strips to screw the outer drywall into?

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