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Sound Proofing


tkam
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I'm helping a buddy of mine convert his unfinished basement into a full-blown theater room.  He wants to sound proof the room so he won't bother anyone in the rest of the house.  Sound proofing is not an area I have much experience in so I'm looking for suggestions as to the best method(s) and material(s) to get this done correctly.  His basement is completely unfinished right now so there's not really any limits to what we can install.

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Honestly, I'd strongly consider hiring a consultant.  Otherwise you're just as likley to get bad results as good.  But it also really depends on the level of expectation.  Are we talking true isloation (which will require significant investment) or merely mitigation?  In my life as a consulting structural engineer I had several experiences with clients wanting anything from mitigation to complete isolation.  Migitation was generally desired by developers of multi-unit complexes where sound transmission (to suome degree) is acceptable but paper thing walls are not and I think this is where you're heading.  The only person that I ever saw successfully implement isolation was Hughes-esque private masion that I'm quite sure is not what your friend is considering. 

 

To get an idea of where to start search for something like "STC rated assemblies" and have a look at this http://www.usg.com/rc/system-catalogs/acoustical-assemblies-en-SA200.pdf.  Skip to the end where you can see some typical construction details. 

 

There is a minor tangential concern with how much weight you might potentially be adding to the first floor framing (basement ceiling) if you really go whole hog and start adding a bunch of shielding material. 

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I'm working on the idea that what your friend wants is to dampen as much sound as possible, without a huge monetary layout. I've had great luck dampening walls by just installing either fiberglass or cellulose insulation in the wall cavities, then installing a layer of drywall, followed by a second layer of drywall with 1/2" furring strips between the two. You can simply use Locktite power grab to glue the 1" x 1/2" wooden furring strips every 16" to the first layer of drywall, the screw the second layer onto those furring strips. Same technique for ceilings. Be sure to tape and float both layers of drywall. This will dramatically reduce sound transfer at a very reasonable cost. A solid core exterior door, or better yet, a sound deadening door should give great results. Two sound dampening doors, one at the top of the stairs and one at the bottom is worth the extra cost IMO.

Edited by swt61
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The basic rule of thumb, to the best of my knowledge, is that stopping transmission requites mass. You really can't stop the lows with damping materials. So Steve idea of multi layered wall board is likely a good one.

 

Sealing doors and vents is a very good idea. It's amazing how much sound can come through a small opening.

Edited by Tyll Hertsens
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I can't completely agree with Nate, as I've indirectly had some bad experiences with contractors, but if your friend finds a good one -- and there are good ones, look at studios -- you can still learn as much as you can and monitor what sort of job they're doing. That said, that's still what I'd do -- go with a contractor. I'd just probably micro-manage them to death...or at least to the point of hating me. I'll post some tidbits later. Sent frum mah phone-blet using Tapatalk.

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I'm working on the idea that what your friend wants is to dampen as much sound as possible, without a huge monetary layout. I've had great luck dampening walls by just installing either fiberglass or cellulose insulation in the wall cavities, then installing a layer of drywall, followed by a second layer of drywall with 1/2" furring strips between the two. You can simply use Locktite power grab to glue the 1" x 1/2" wooden furring strips every 16" to the first layer of drywall, the screw the second layer onto those furring strips. Same technique for ceilings. Be sure to tape and float both layers of drywall. This will dramatically reduce sound transfer at a very reasonable cost. A solid core exterior door, or better yet, a sound deadening door should give great results. Two sound dampening doors, one at the top of the stairs and one at the bottom is worth the extra cost IMO.

 

The cellulose insulation with two layers of drywall (with a gap between layers) is exactly the direction we've been thinking about going.  It should be the most cost-effective and I think realistically will give the best performance per dollar vs some of the other crazy solutions out there.  My friend does want to have a contractor/home theater installer come out so we will see if they agree with this or recommend something else.

 

I'll definitely mention the idea of new doors (for top and bottom of stairs) as I don't even think the ones in place are solid core.

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So the only points I was going to add or reinforce to what has already been said:

 

With basements, you have to be careful that you don't block air flow, because humidity tends to accumulate in the basement, and you don't want to set up a mildewy environment.

Which is actually contradictory to everything else you want to do, which is make as complete a sound seal between the two floors as possible.  Doors are a big deal in studios, but pretty much every hole is going to be a source of sound leakage.  So you kind of have to mitigate one against the other.  When I was planning on building a small home studio in the basement of my former landlord's house, I was thinking of devising a system of letting the room breathe when I wasn't using it, and sealing it up when I was.

The duct work is a good point -- it's just like a car, you have to cancel both sources of noise and rattle, but it's also a conduit for sound leakage.

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I have a vague recollection that putting a 360 loop in vent ducts dramatically reduces its ability to transmit sound. Prolly should go look in my "Handbook for Sound Engineers."

 

 

......goes and looks....

 

Nothing about 360, but they do suggest a "plenum."

 

http://www.audioholics.com/education/acoustics-principles/a-guide-to-sound-isolation-and-noise-control/fig3hvacsystemsehx.jpg/image_view_fullscreen

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I have a vague recollection that putting a 360 loop in vent ducts dramatically reduces its ability to transmit sound. Prolly should go look in my "Handbook for Sound Engineers."

 

 

......goes and looks....

 

Nothing about 360, but they do suggest a "plenum."

 

http://www.audioholics.com/education/acoustics-principles/a-guide-to-sound-isolation-and-noise-control/fig3hvacsystemsehx.jpg/image_view_fullscreen

 

I know I've sent sound diffusion for vents, but don't remember where. 

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I believe the part of the basement my friend is planning on using for the theater project should get us around any potential duct related issues.  I'll have to double check for sure though.  The basement in total is pretty damn huge so we're likely just going to be walling off part of it.

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Sorry, one more:  sound-proofing is more the territory of home studios than it is home theaters, so I would look there.  For example, you might want to dig through back issues of Sound on Sound magazine for a column they do regularly called "Studio SOS", which suggest a lot of cheap alternatives and solutions that work within weird requirements (like Spousal Acceptance Factor, working within a budget, or being stuck in one particular room).  You can read the first couple and/or last couple paragraphs to tell if the entire column would have anything that would help you.

 

Alright, two more (this being the second):  sound leakage prevention isn't the exact same thing as sound-proofing -- you only have to worry about conduits to the rest of the house, rather than isolating the whole room.  Which, in the basement's case, means mostly the ceiling.

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  • 5 months later...

Gearslutz is probably the worst named forum ever. Googling sound absorbing panels and acoustic panels brings things like these:

 

Acoustic-Panel-Microsuede-E.jpg

 

225761_10150237647807329_653462328_87885

 

Seems just what I was looking for. Was just wondering if you guys had tried a particular version of these that worked well. If not, I'll just keep researching.

Edited by mypasswordis
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Agreed, but those are real musicians and music producers (amongst a bunch of amateurs like me), so you're going to get real world advice.

 

I was looking into soundproofing for a while (when I was going to set up the studio at Linda's) -- the one piece of advice I remember is, if you need full-on soundproofing, you need a seal.  So just panels won't cut it, you need to cover the entire wall/floor/ceiling.  For example, I live on a top floor apartment, but there are rooms between me and the neighbors, so I only need to do the floor...but I would need to do the whole floor.  Probably especially worthwhile would be to create a removable cover for the ductwork, since it acts like a VPN through a firewall.

 

The other piece of advice is weight -- sand, kitty litter, lead, concrete, that kind of thing.  The more molecules you have densely packed together, the more they'll absorb the energy rather than transmit it.  Lead sheets.

 

Lastly -- cater to your needs.  You only need to attenuate a certain frequency range by a certain amount, so I would find out exactly what that is, and shoot for exactly that.  A lot of room treatments are for low frequencies, but like I mentioned with the vocal mic -- you don't need to worry about that.  For example, I wouldn't be able to cover my entire floor in the open area with lead sheeting, but if I knew I was always going to make most of the noise by the monitors/guitar cab/etc., I'd make sure that area attenuated the most, and that it was centered.

 

Another suggestion if you have the budget is to get a large vocal booth, like that guy who used to hang out on headcase and I think he suffocated.

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Good points all around, thanks. Lowest note on the violin is around 196Hz so thankfully I don't have to deal with the bass, which I read is the hardest to attenuate. I read up on the two main measurements/specs they do, STC (Sound Transmission Class) and NRC (Noise edit: Reduction Coefficient). So I want high both, without the panels being too ridiculously heavy since hanging really heavy things on walls with nails sounds like a bad idea to me. And they thankfully don't need to be too heavy because I only need attenuation from 196Hz and up. Not sure if it's feasible to seal everything, but I may be able to cover most if not all of the one wall in question (adjacent to my neighbor).

 

Wtf at some guy on HC that suffocated? I'm totally unaware.

Edited by mypasswordis
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Just my theory.  He got one of those portable vocal booths (and no, it was not bigger on the inside), made a couple posts after that that he was doing all his listening in the booth, and then promptly stopped.  Almost like he had bought JH Audio something or others.

 

And no, you don't need to seal everything, that was my point about attenuation.  Find out what the walls already attenuate, find out how loudly you play, decide how quietly you want to be heard, what remains is what you need to attenuate by.  No seal == still attenuate a lot, as long as you do things smartly like block the ductwork.  In other words, concentrate on the problem areas.

 

And you don't need to hang the lead sheets from the walls, as long as you place them between the sound source and the largest conduits.

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I am actually practicing in somewhat of a booth right now, so maybe all I need to do is put it up some stuff on the "booth" walls and then some light stuff on the wall adjacent to the neighbor. Only way I can really know how much the walls already attenuate is getting somebody with an SPL meter to stand in the neighbor's room while I play in mine (and then compare with SPL meter right in front of me). So far I'm just guessing how much it attenuates based on what I hear of their voices and movements through the wall. I'll do some more research and hopefully come up with a solution. You are lucky to only have to deal with the floor, I feel like rugs would take care of most of the problem.

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I found a material called Porous Expanded Polypropylene that does small to medium amounts of both sound absorption and transmission loss, which is what I'm leaning toward now. http://www.soundaway.com/Echo_Drop_PEPP_s/119.htm Most of the soundproofing materials I read about are supposed to go between the studs behind the drywall, there isn't too much that can help just mounted straight onto the wall but the PEPP is one of them. I'm pretty sure the walls are concrete. 

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