Wall construction - thin drywall, impact on bass?

AudioExplorations

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Apr 5, 2012
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I have my system setup in a very small room in the attic as I have just moved house and am getting the larger listening room setup. I was expecting severe bass modal issues due to the room size, however the response seems to be extremely smooth (I have yet to get out the mic and measure to confirm).

The house is a prefab construction, steel frame with elements slotted in to form the outer walls. The inside structure is made of dry wall, two layers around a centimeter thick, with a bit of air in between. I believe the attic floor is made of relatively thin wooden floorboards likely hollow to house the steel frame, with a further drywall layer underneath to make the ceiling downstairs.

Is it possible the bass is permeating through the walls (and floors) due to this lightweight construction?

Is anyone aware of documentation that shows frequency transmission behaviour of different wall types/thicknesses? Any insight on this would be appreciated!
 

jiannone

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Dec 4, 2013
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Is anyone aware of documentation that shows frequency transmission behaviour of different wall types/thicknesses? Any insight on this would be appreciated!

Gypsum and Fiberglass are dense and popular for low frequency absorbers but unless your drywall is extraordinarily dense, the bass from your system is probably not interacting too much with the walls. It could be really good cancellation modes too.

Some resources:
http://www.bobgolds.com/AbsorptionCoefficients.htm - Here's what you're looking for.
http://www.mcsquared.com/wavelength.htm - 344Hz is 1 meter
http://www.acs.psu.edu/drussell/demos.html - How sound moves

JBL put 10" of wall material in their listening room.
 

dallasjustice

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Apr 12, 2011
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It's a good thing for the LFs to exit your room. The only downside is if the walls are playing along with the bass; causing distortion.
 

AudioExplorations

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Apr 5, 2012
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Thanks for the various info.

It's a good thing for the LFs to exit your room. The only downside is if the walls are playing along with the bass; causing distortion.

My thinking exactly. This is what seems to be happening for me. No more need for bass treatment or sub 200 Hz EQ-ing, which is amazing.

Downside is of course that the whole house is bobbing along to my basslines... :)
 

microstrip

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May 30, 2010
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IMHO you should get "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms", chapter 22 "Designing listening experiences". F. Toole also describes some of his experiences that will be of great interest to you.
 

ALF

Well-Known Member
Mar 15, 2012
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Phase...

I have my system setup in a very small room in the attic as I have just moved house and am getting the larger listening room setup. I was expecting severe bass modal issues due to the room size, however the response seems to be extremely smooth (I have yet to get out the mic and measure to confirm).

The house is a prefab construction, steel frame with elements slotted in to form the outer walls. The inside structure is made of dry wall, two layers around a centimeter thick, with a bit of air in between. I believe the attic floor is made of relatively thin wooden floorboards likely hollow to house the steel frame, with a further drywall layer underneath to make the ceiling downstairs.

Is it possible the bass is permeating through the walls (and floors) due to this lightweight construction?

Is anyone aware of documentation that shows frequency transmission behaviour of different wall types/thicknesses? Any insight on this would be appreciated!


Hello AE,

Your question reminds me of another fellows quest for better sound. I believe that after removing all of his Sheetrock, etc., he found that the builder of his speaker, along with himself, failed to realize that issue was resultant from the speaker, not the Sheetrock.

It seems that the speaker was simply wired out of phase, imagine that! After all of those years of in-the-seat listening, the speaker builder was deaf to his design.

Best of luck, and read some of the above-mentioned resources, very good and solid recommendations.

Cheers,
ALF
 

AudioExplorations

New Member
Apr 5, 2012
653
5
0
IMHO you should get "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms", chapter 22 "Designing listening experiences". F. Toole also describes some of his experiences that will be of great interest to you.

Embarrassingly I have this book and didn't think to look there as a first step, shame on me! :) Thanks for the reco.
 

DonH50

Member Sponsor & WBF Technical Expert
Jun 22, 2010
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I would expect wall flexing to have negligible impact on the sound in the room. Might even improve it if the walls absorb energy and reduce the magnitude of room modes. The most impact is probably lack of isolation, as has been stated (i.e. you're fine in the room, but annoying everyone else in the building and perhaps beyond).
 

Nyal Mellor

Industry Expert
Jul 14, 2010
590
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330
SF Bay Area, CA, USA
Generally I see rooms with single sheetrock have more ringing but less peakiness. The walls are flexing to absorb the bass but then they are ringing / resonating on. The effect is most pronounced below about 150Hz. Double sheetrock walls with green glue don't exhibit this ringing/resonance but since they contain the sound energy tend to result in a more peaky bass response. Interestingly sheetrock on isolation clips / hat channel turns into a very very good bass absorber below 60Hz.
 

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