Help on sound proofing a room (1 Viewer)

[Andrew P]

How would I sound proof a room (or at least cut down on) the sound without having to turn down my amp to such low levels. Any ideas or comments would be greatly appreciated.
Andy

 

[Jay Mitchosky]

Moving to building a HT.
Sound proofing an existing room is a pretty tough thing to do. You can insulate the walls if they're not already, and apply another layer of drywall or soundboard. But you'll still be hobbled by an element not easily reversable - the frames and studs. Sound vibrations are easily transmitted through a conventional wall as the sheetrock and frame are connected. Ideally a soundproofed room would have separate frames not physically connected so the vibrations aren't easily passed. Two layers of drywall overlapped (with staggered seams) and some sort of sealant or caulk provide further support. You need to isolate the room, and to that you need to seriously renovate.
Also note a huge culprit of sound transmission: the door. You likely have a normal interior door to your room that will easily pass sound from room to room. An exterior grade door, insulated and mounted with weather stripping, would do a better job.
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--Jay
"No one can hear when you're screaming in digital."
My Home Theatre Pictures...
"You're no mesiah. You're, you're a movie of the week. You're a ... t-shirt, at best."

 

[Darren Hunt]

If you decide that your going to gut the room and start putting up staggered stud walls and double drywall, be aware that the walls will be great, but like Jay said, the door will be a big problem unless you buy an exterior grade door, or have a custom made one that would cost a fortune. On top of this, you will also have trouble with your ceiling as in most homes, the ceilings are not high enough to do any serious sound proofing without lowering it to the degree that your combing your hair every time you enter the room.
If your room is large enough, you could also always build the interior wall within the existing room, essentially having a double wall (I think Jay hinted at this as well). This will cut down on your available room by quite a bit, but it would offer serious sound proofing as you would essentially separate your room from the rest of the house (except for the ceiling again - argh!). If you do this, you can also consider a double door entrance to the room (1 door, a short hallway, and then the entrance door) with the appropriate seals on the doors. This double door system is cheap and very good at keeping the sound in, but takes up quite a bit of space.
In the end, the level of sound proofing will be as high as the weakest link in the system (that most likely being the ceiling, door, or walls if left alone).
Darren

 

[Michael Ipp]

You also should be careful on what you use to soundproof your room. You might wind up removing certain frequencies by mistake. Sheet rock is a good insulator and doubling it up does even a better job BUT sheetrock absorbs lot of low frequencies.
Example from Master Handbook of Acoustics 4th ed.
An open window has an absorption coefficient of 1. Which means it absorbs ALL frequencies (in reality and frequency that goes through an open window does not return, so it's considered absorbed)
A 1/2" sheet rock has the following absorption coefficient:
125hz = .29
250hz = .10
500hz = .05
1khz = .07
4khz = .09
So you can see that by doubling up you sheetrock you will be absorbing more bass. That might be good or might be bad depending on your room. Just keep it in mind

 

[Dave Miller]

Andrew, I hope you don't mind me jumping in here, but I have a question for Darren (or anybody). If your HT room is on the lowest floor in the house, then how do you sound proof the ceiling of that room? You are cautioning that the ceiling could be the weakestlink (this is now one word thanks to that British chick), so what's the solution?
Peace,
DM
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"We all end up dead, the question is how and why."

 

[Andrew P]

Im more worried about the side walls because I live in a condo (townhouse style) and I dont mind the sound upstairs, but I was hoping to keep the majority of the sound away from the nieghbors. Right now I have such little bass because I am afraid of too much noise.
Andy

 

[Darren Hunt]

Dave....
When I built my room, I tore everything apart in the room. I then did the staggered stud thing as well as acoustic tracking (resilient tracking) with drywall. I realize that it has absorbed a bit of the low frequency, but I am still very happy with the results. With my ceiling, I wanted it to be high, which automatically limited my sound proofing options seeing as I couldn't move it to make it higher. I decided to go with a diffusion ceiling by building in between the jousts. As it stands now, I have 8" of insulation packed (more like squished) within a 1.5" space, covered with drywall BETWEEN each joust. I thought this would help a bit at dampening the sound travelling upstairs. I then hatched my ceiling with 2x8's to create a checker board effect, using the existing jousts. I am then going to place 3D diffusion blocks (approx 8"x8"x6") within each hole in the ceiling (currently working on this). This will hopefully allow the sound to be diffused around the room, and again, keep some of it from travelling upstairs (can't do much about the low frequencies here). I figure this is better than a flat ceiling which would give me a bad first reflection to my seating positions.
My biggest problem is that I have to use the existing jousts that connect the upstairs floor to my room. They make great sound conductors and ensure that the sound will reach upstairs, no matter what I put between them (which is a BAD thing).
I guess if I had not wanted my ceiling to be so high, I would have filled the space between the jousts with insulation, then placed rows of resilient channel and screwed drywall into the channels to separate the jousts from the room as much as possible. This would result in better sound proofing between the upstairs room and my room, but would have also ended up with a lower ceiling, and a large, flat area that would cause a huge 1st reflection that would be difficult to handle (unless I wanted to start lining the ceiling with absorption panels). In the end, since the room above is a living room with a dining table, it wouldn't be a big deal if some sound made it up there. Had it been a bedroom, I probably wouldn't have bought the house.
If I had built my house from scratch, I would have probably asked for 10 or 11 foot tall ceilings, just so that I could use a good foot to separate the ceiling from the upstairs, AND allow me to do something about the flat surface. But, I bought a used house so that wasn't an option.
Darren