Soundproof Listening Room

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According to Gedde's home theater book there's supposed to be a "channel" in a sound proof wall. I don't understand what the channel is there for. Has anyone figured this out?

I know a thing or two about horns, but I'm new to soundproof rooms.

I understand the concept of having two isolated walls, with staggered studs so that the two walls don't actually touch. But what's the channel there for?

The studs are attached to the wall right?

home theater book i just read
 
Not really sure what the "channel" would be. My guess that it is just the space between the two stud walls.

I am an Architect and have worked on a number of designs with acoustic engineers that have involved room acoustics and sound proofing. Basically the best scenario was to have a central wall of high mass [precast / off form concrete wall say 50 - 100mm thick or concrete filled block wall]. This limits the transmition of lower frequencies. Either side of this you build say a 90 x 45mm stud wall that is disconnected from the concrete wall. This stud wall is then infilled with acoustic insulation. Line the stud wall with 2 - 3 layers of plasterboard, preferably fire rated [it's denser] or altenatively a compressed cement sheet has more density [the denser the material the better]. The ceiling and floors also need to be treated in a similar way as the room will only be as "sound proofed" as your weakest link. Everything needs to be isolated from room to room. This can be done via suspended ceilings or resiliant rubber mounts so that you fix the wallboard via an isolated acoustic mount. This will limit sound transmission to the building structure and hence stop it from traveling to other areas. The engineer even taked about having a separate concrete slab for the sound proof roof. The room also needs to also be air tight so caulk all joints between wall board, door + window seals etc. Room treatments can also be used to break up standing waves and improve the performance.

Staggered studs is just another way to go but is not quite as efficient and is basically just a way of making the wall thinner because as you can tell the walls start to get quite thick!

Check out "The Red Book" in the link below. It shows a large number of possible wall constructions and their Rw rating [sound proofness]. You will get the idea that more is better...

http://www.gyprock.com.au/downloads/filemanager/designguides.aspx?fileIteration=144
 
Channel ???

The channel is a metal extrusion (often "Z" shaped) that decouples the drywall from the studs. It's usually installed horizontally on 16 inch centers and then 1 or 2 additional layers of drywall are then screwed onto it. I understand that applying "Green Glue" to laminate the drywall is the way to go, at least according to the pros.

HTH's,
TerryO
 
ACCUPROAV said:
I HAVE USED THE CAVITY TO FURTHER INSULATE W FIBERGLASS .

ALSO HAVE USED INSULATING RUBBER UNDER THE DRYWALL FOR LESS TRANSFER OF VIBRATION. THE MORE ISOLATED THE SURFACES ARE INCLUDING THE FLOOR AND CEILING STUDS THE BETTER.


PLEASE TONE DOWN WITH THE CAPPS (capital letters), please and thanks. We can all hear you just fine.
 
I've done some soundproofing for home recording. To me, the number 1 thing is air sealing the room - any leak, and all sounds go right through. Similarly, any windows have to be boarded up - sound goes right through them. The special construction of walls/ceilings is for low frequencies, which seems like less of a problem to me - its just a fraction of all the frequencies in sound. Particularly, if your neighbors are in a physically separate building and you've sealed the room and windows, even if there are very loud drums in your room, inside their house it would be barely perceptible. If, on the other hand, your wife doesn't want to hear your sub, or you're in an apartment building, thats a lot more difficult. But without an air seal, all those special walls would be useless.

The last room I soundproofed (sealing doors and windows), we would play extremely loud (drums, guitars), and outdoors, standing next to the room, it was barely noticeable. I'm sure my neighbors couldn't hear it inside their houses.
 
channels are use to reduce effect of noise and to dampen the sound waves,so resilient metal channels can be inserted between one of the drywall walls The resilient channels act as shock absorbers, greatly reducing vibrations coming from either side of the wall from passing through the wall. Absorbent mat is used inside the wall to cushion the channel/drywall and to provide an absorbent compartment to trap sound waves.
 
Sir, I am very insulted by the size of your text! Do you know that occupied 5 millimeters of screen space instead of just 3?

The nerve!

Dear Doctor,

I have to say how much I admire the extent to which you excersise control over your emotions.

Or maybe not, seeing as you've let your internalized anger fester for nearly three years. I wouldn't think that would be very healthy at all.
:D

Best Regards,
TerryO
 
Can you say Z-girts on party walls? If you can you're halfway there. Add green glue for constrained layer damping between two layers of drywall on each side. Double it up with a 3" gap between walls and you're done. If you have to worry about the overall thickness then you're not as concerned about it being soundproofed as you think. Even one of these walls will be pretty inert and about 12" thick.

Brother Terry knows about these things. I just typed what he did with a few extra words thrown in. :)
 
First thing I would like to say is, to do this properly takes careful planning and more money than you think. And while your planning sound isolation keep in mind the room acoustics, they go hand in hand.

He may also be talking about cutting a slot in the floor between the walls to acoustically isolate the floor in one room from the other.

Other tricks, make the layers of drywall on the 2 walls different thicknessess so there resonant freqs are different (this is the freq they let the most sound thru, usually 20 to 50 hz depending on construction). Put as much mass in between the walls as possible. (In extreme cases Ive seen cinder blocks filled with sand)

And if your building from scratch angle the inside walls so the space between changes with lenght (the room is wider at the back or coffin shaped). This is even more important for the room acoustics to optimize reflections and reduce the effect of room modes. If your concerned with leakage thru the floor there are isolaters for that too.

You should be able to find this and more info on the net, or if your going to the trouble of doing this invest in a book or go to the library. Most books that deal with recording studio room design and construction devote a large part to sound isolation, including the all important doors and windows. And the rest to acoustics (reflections, absorbtion) and even making your aircon quiet. They should show you the exact materials and construction methods. Good luck.
 
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If the reduction of sound transmission is the goal (STC Rating), then RC1 or resilient channel shaped like a Z is helpful. RC1 also has to be installed with the bottom leg screwed to the existing wall or studs and the new GWB attached to the top leg so that the weight of the drywall pulls the channel down and effectively creates a spring. Hat channel or RC2 will not help reduce sound transmission alone. If hat channel is used, it should be used in an rubber isolation clip like this one:
Resilient Sound Isolation Clips - Model IsoMax - Wall Clips and Ceiling Clips
Room acoustics are an entire different animal but the OP is referring to sound proofing which is essentially creating a high STC rating. There are a ton of ways to pull this off but a couple layers of GWB or even Quietrock GWB and/or mass loaded vinyl behind GWB are the easiest short of dedicated, designed rooms.
 
IRoom acoustics are an entire different animal but the OP is referring to sound proofing which is essentially creating a high STC rating. There are a ton of ways to pull this off but a couple layers of GWB or even Quietrock GWB and/or mass loaded vinyl behind GWB are the easiest short of dedicated, designed rooms.


I am not familiar with the mass loaded vinyl technique.
Could you point to where I might find out about this?
Thanks
 
mass loaded barrier = sound barrier = deadsheet = sheetblock = limpvinyl = high mass layering = high density vinyl = polypropylene fibre reinforced bituminous mixture = polycarbonate sheet....

The technique is simple: flexible sheet of high mass that blocks sound that is transported trough air or contact sounds that are transported trough materials. In most cases it is reinforced by fibres to prevent stretching under its own weight in case it's hanging.

It can be used as a layer in between, free hanging with absorption materials in front and/or behind it and a few other ways.
 
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