Author Topic: Changing floor, best way to improve noise isolation  (Read 12117 times)

whatismisophonia

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Re: Changing floor, best way to improve noise isolation
« Reply #15 on: March 10, 2013, 03:23:30 AM »
Smoss, the reason I was complaining about lightweight drywall is because if you compare similar wall constructions, each with different amounts, types, and thicknesses of drywall ( http://archive.nrc-cnrc.gc.ca/obj/irc/doc/pubs/ir/ir761/ir761.pdf ), you can see how increasing the mass of a given wall has it's greatest benefits at the high frequency and low frequency resonances.

And the reason I was mentioning damped drywall is because aside from increasing the mass, one of the best ways to alleviate these resonances is by damping the drywall ( http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=20374559&article=0&fd=pdf ).   

Bare in mind that i'm not talking about moving the resonance to a lower frequency, but reducing it at the frequency where it is.
There was an attempt a moving the LF resonance to a lower frequency in your building, but as you can hear (and feel), the resonance is still there.  Although the panels can always be more decoupled to reduce structral resonance (definitely remove crown molding and redo edges), you'll still have the mass-air-mass resonance to condent with; that must be reduced via drywall mass and damping, unless you could somehow create a strong vacuum between the panels (sound cannot move through a vacuum, such as in outerspace, which is obviously not currently realistically feasible).

p.s. to johnbergstromslc, I know the lighter stuff is not light enough to make a huge difference, but my point is how incredibly far off course the industry is, and all for the sake of short-term dishonest profit by way of selling people more air and less gypsum. 

Also, so as not to confuse smoss, a basic decoupling job will not be enough at the low frequency resonance because it just moves it to a more annoying frequency; it's only a start in the right direction, as soundproofing in general is more effective above the resonance.  JB is always advocating tripple drywall w/ greenglue so long as the structure is decoupled well enough.  Your resilently mounted stystem is not really the bees-knees for decoupling, but just the same, I would advocate extra drywall and damping at this point if you're not finding any better soundproofed buildings elsewhere.

johnbergstromslc

  • Guest
Re: Changing floor, best way to improve noise isolation
« Reply #16 on: March 10, 2013, 07:39:27 PM »
Did a little research on the subject of lightweight drywall, and it looks like even if it becomes the norm (it probably will - more efficient use of resources, easier on the backs of the installers, etc..), the regular density, 5/8" type-X stuff will still be around.  If they tried to make type-X lightweight, it would greatly dimish it's fire rating, and that aint gonna happen... 

For soundproofing applications, you should be using 5/8" anyways...  You may need to throw on a 1/2" panel to vary the density on one side to avoid resonance, but, as a rule, always start with the thicker stuff.

The 'Great Drywall Crisis of 2013' is averted.  You're welcome - LOL.