# sound isolation



## mike c (Apr 25, 2006)

hi

I have moved my HT setup to a room that has one wall that's made of dry wall, instead of the usual 4 walls with concrete. I got a noise complaint from the adjacent room ...

I have UP to 12" to work with, I can't use concrete now, I can build a new drywall next to the existing wall in question ... possible materials are wood and fiberglass ...

I was thinking two layers of 3/4" plywood plus some fiberglass before topping off with a 1/4" plywood would give me a free bass trap, but would it be sufficient to isolate the sound?

if not, can you suggest configurations of drywall building that will stop both the high bass and the low bass?

thanks
mike


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## John Simpson (May 10, 2007)

There's been a couple of "sound insulation" threads started recently. Here's one, and you could probably trawl the "Home Theater Design and Construction" forum for a bunch more.

If that doesn't help, feel free to post again.


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## mike c (Apr 25, 2006)

thanks, but that thread has nothing new to add to what I already posted regarding adding a second dry wall.

dial up connection at work prevents me from surfing my heart out.


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## bpape (Sep 14, 2006)

If you're going to build a second wall ( a good idea by the way), remove the drywall from your side of the existing wall first. If you don't, then you're creating what's known as a triple leaf which can actually INCREASE sound transmission at certain frequencies.

Build the new wall as far from the existing one as you can, fill the space fully with insulation, use slats parallel with the floor and perpendicular to the vertical studs, and finish with at least 2 layers of drywall.

The slats will act as a poor-mans RSIC/Hat Channel setup, and the double drywall is MUCH more massive (good) than plywood. Also make sure you caulk up all around the wall. You will likely also need to consider doing another layer of drywall on the ceilng to avoid flanking. Hopefully, the floor won't cause too much problem.

Bryan


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