Soundproofing Reviews

I think this should be the most valuable forum to date!

I agree, we read about people constructing sound proof rooms based on tested assemblies with high STC ratings and total isolation (room within a room) but I have yet to read anyone commenting how well they contain sound with the room, especially LF's.

I'm about to embark in constructing a room within a room for a dedicated home theatre / 2 channel listening room.

Over the last 4 years I have read many books, 'white papers' regarding sound proofing as well as acoustical treatment within the room.

One of the best sites I've found for sound barrier walls and STC ratings as well as how to determine the resonant frequency of cavity spaces is from the Canadaian Goverments 'Nation Research Centre (NRC)' They test wall asseblies, material etc for sound ratings and not skewed by travelling sales men looking for a good rating on their product as I'm sure everyone knows there are alot of 'snake oil' products on the market these days.

Feed back from AVSforum members regarding the construction of there rooms and the end results would be an invaulable discussion forum.

This thread may be what you are looking for: http://www.avsforum.com/avs-vb/showthread.php?t=1298384

Since most of us don't have real "before and after" states to compare, we have to rely on the experts and (of equal importance) the lab data to say what works and what doesn't. If there wasn't an identical setup in the room "before", the "after" results are hard to quantify. Just about everything talked about here will make some difference...

This post has an excellent test, though, showing the difference Green Glue makes:

http://www.avsforum.com/avs-vb/showt...php?p=21203262

I found that simple test to be a great way to see that it was in fact "doing something"!

Jeff

These variables have been tested, so there's hard data to look to in addition to anecdotal.

We know foam is bad

We know fiberglass is great and cheap

We know that we want all the mass we can get, hence double or triple 5/8" drywall.

We know that we want decoupled framing.

....and STC ratings don't mean squat for Audio playback spaces and, in fact, can be highly misleading. Do not use them!!! Get the transmission loss data. Also note, you cannot (as some have attempted to do) is add them together. IOW, if one layer of a material is STC 25, putting two pieces of that material together will not result in an STC of 50.

OK, here's my anecdotal results, since I didn't take measurements before starting. I wish I had. My open concept room is not finished, although, for all intents and purposes of this discussion, "sound proofing" is done (I'm currently working on in-room treatments, which, as we should all know by now, is different).

Methods I used:
1) DC04 on ALL stud walls
2) Clips and channel on entire ceiling (yes, even the bathroom - no embarrassing noises getting out of MY bathroom!).
3) R19 in entire ceiling
4) R13 in ALL walls
5) 5/8s Fire Rated DD + GG on ALL walls and ceiling

Family room is directly over theater area of room.

Prior to drywall, I could clearly hear speakers sitting on floor above. I could hear music from upstairs throughout basement and music from basement upstairs.

After drywall, there is a zone along the hallway leading to the bar/theater area, where I can hear music from upstairs AND in the basement. Once you cross the zone, you can no longer hear ANYTHING from upstairs, even with the door open. And that is the one thing I haven't treated yet.

You will not ever find a "before" and "after" (at least not in this neck of the woods). You may find such data under lab conditions as part of a very well funded research project.

The only way you can get a valid before and after is to first fully construct and treat (interior room acoustics only) the room. Measure the transmission loss of each wall (floor and ceiling). Completely remove all drywall, HVAC, electrical and insulation from the space and rebuild the space using the proposed techniques, processes and materials, then remeasure the transmission losses of each wall. If you're willing to expend that capital and time, please do so. Note however the measurement equipment will be very expensive (the appropriate microphone alone will be in the $2000 range) and the equipment typically used by non-professionals will be far from adequate for these purposes.

I recorded myself doing a knock test on some drywall. I knocked the same strength on each part. All knocks are done with an open back (drywall not put in yet on other side of the false wall and no insulation is installed yet). I knocked on a single layer of 1/2" drywall, a double layer of 1/2" drywall without GreenGlue, and a double layer of 1/2" drywall with green glue. You can hear the differences.

Photobucket shifted the sound slightly off the video when it transcoded it, but not enough to remove understanding of what I was doing.

http://s113.photobucket.com/albums/n...KnockTests.mp4

I'd be interested to see the results after 3 more weeks. The last panel still sounds a bit "wet," plus you're hearing a good amount of echo off the face of the board

My room is a room within a room with the exception of one wall that is staggered stud and clips and channel for the ceiling. I used a layer of OSB and 2 layers of 5/8 drywall with green glue between each layer. My room is not completely done yet, I still have to seal my door and seal off a few wire runs into the room but I can say that the room is very effective. Higher frequencies are pretty much completely attenuated at just about any level, and the low frequencies are reduced significantly. I think I am going to be more than happy with the soundproofing once everything is up and running.

I am also very pleased with how quiet the room is inside. Its actually a bit of a strange sensation because I'm not used to being in an environment that quiet.

This is exactly my experience after 6 months with a completed room. Same setup with OSB-GG-DW-GG-DW (5/8") and a weather-sealed solid core door. I have a dead vent as well for ventilation. Very quiet in the room to the point it's eery. High frequencies are contained, low frequencies are attenuated but do escape and cause some vibration during bass heavy scenes.

That last bit of low frequency isolation needs more mass. Same basic techniques of decoupling, absorption, mass and damping, but with more mass.

I think what we are looking for with regards to 'before and after' is based in people's construction methods, how well does the dedicated room prevent sound from entering other rooms, not acutal TL #'s, but...'I can only hear a faint thump upstairs..and here's how it was constructed....'

Question, when constructing a 'room wthin a room' and the outer wall runs perpendicular to the floor joists, do yo install wood blocking and carry the 2 layers of DW up to within a fraction of an inch to the flor sheathing? or just fill this cavity with batt insualtion?

There is no performance difference between Roxul and equivalent fiberglass ... but, you're free to listen away.

If you construct a room within a room as follows:

Inner wall
5/8" DW
Green Gluu
5/8" DW
2X4 wood studs @ 16" o/c (10' - 12') no wood blocking bewteen studs)
4" batt insualtion

5" air space

Outer Wall
2"x6" wood studs @ 16" o.c. (9' high wall with wood blocking between studs
6" batt insualtion
5/8" DW
greem Glue
5/8" DW

Adding wood blocking between the studs would increase the stiffness of the wall, what effect will this have on TL for low frequencies?

None

Would a stiff wall (of same construction) perform differently than a limper wall when it comes to sound transmission?
I would think that a limper wall would vibrate more thus dissapating more energy?

Do you know if there has been any test performed for a wall as follows:

Construct 2 seperate walls with an air space bewteen them, lets say 6" and install a dense limp material which would vibrate at a certain frequency, would this helkp with reducing that frequencies energy and help reduce that frequency from being heard on the other side of the wall?

Ted, what is the cure time for green glue and what consistancy/colour is it fully cured?

If it is a coupled wall (single stud), more flex is more isolation. In a coupled wall, 24" OC framing is more flexible than 16" OC, so 24" is better. In a coupled wall, 25 ga steel studs are more flexible than wood, so 25 ga steel is better than wood or 20 ga steel studs. A 24" OC 25 ga steel stud wall has a similar TL curve to Resilient Channel (RC-1). Again this is with a single stud wall. In a decoupled wall, this is much less of an issue.


Have not seen any such test, nor likely will I. If this hypothetical middle layer were to have any effect on a low frequency wave it would need to be massive. A massive layer would constitute a leaf, and a triple leaf would exist with lowered performance at most frequencies relative to the original wall.


Cure time varies with drying conditions just like with paint. Generally it is suggested to allow 30 days to dry. If wet, the tiny polymer sections have not joined up to create long cross-linked polymer chains that yield effective damping.

Color is a dull light green. Consistency is is a very viscous slime toy. Pull on a piece and it slowly returns to its original shape. It will always be sticky.

the only thing I canthink of is Roxul may have a greater denisty than the regular pink batt insulation thus offering more resistance, but I would tend to think this is minimal.

The higher density of the mineral product give a slight high frequency advantage in a sealed cavity like a wall. Slightly lower density fiberglass, however, gives us a slight advantage in the low frequencies. Given that the low frequency isolation is our focus, and the stuff's cheap, we choose fiberglass.

Here's my two-cent soundproofing review...

In 2007 I finished building a multi-media / theater room in my basement. Sound proofing was a huge concern to me. Since my room is not a single "dedicated" room, I decided to apply the soundproofing methodologies discussed here on AVSforum to my entire basement.

The bottom line after almost 5 years of using my theater is I am still absolutely thrilled with results. The soundproofing effort added a significant amount of time and cost to my project, but I would do it again in a heart-beat.

I can crank my audio system up to ungodly levels and in the room above my theater, only a tiny bit of the bass is noticeable (dual SVS Ultra subwoofers). In the second story upstairs master bedroom, my wife can easily sleep while I watch a late-night movie at any volume I desire. As for outside sound getting into the basement, the basement is so quiet that when my kids come home from college, they always want to sleep in the basement bedroom because they can sleep as late as they want and never hear anything from upstairs or outside.

As a comparison, I helped my neighbor with the wiring and audio system in his basement media room when he had his basement finished. Both of our homes were built by the same builder in 2004. He hired a contractor to finish his basement and the contractor used standard building techniques with nothing for soundproofing other than fiberglass insulation in the ceiling. All I can say is the difference between his basement and mine is like night and day.

The soundproofing techniques I used included:

1) Floor - I have a structural wood basement floor over a crawl space (something they do here in Colorado due to the expansive soils). I added a second layer of 3/4" OSB with GreenGlue between to the entire floor.

2) Walls - All walls in the entire basement are decoupled from the rest of the structure of the house using isolation clips. Walls are two layers of 5/8" sheetrock with GreenGlue between. I was extremely careful with all penetrations (outlets, light switches, etc.) to carefully seal everything.

3) Ceiling - Isolation clips, hat channel, double 5/8" sheetrock with GreenGlue. I put in some recessed lighting, but I built double-layered 3/4 MDF boxes with GG to house the recessed canisters.

4) HVAC - I put the entire basement on a separate HVAC zone and fed all registers with flexible ducting with at least one "S" turn in the run. Return air runs through a sound attenuation baffle with additional flexible ducting and "S" turns.

5) Doors - I have double communicating doors (exterior grade with full seals) between my theater and a furnace room that is in the basement. I also have exterior grade doors with full seals at the top and bottom of the stairs going to the basement.

6) All pipes that were routed in the ceiling of my basement (HVAC, sewage, etc.) were wrapped with an adhesive backed sound-deadening MLV product similar to Dynamat.

7) Insulation - I used standard fiberglass insulation in the walls and ceiling.

(I have to give an unashamed huge "plug" for Ted White. I dealt with him just after he had started into GreenGlue and I bought a boatload of product from him. I also met him briefly when he was at CEDIA here in Denver a few years ago. All I can say is he is one of those guys that you really feel good about working with. His customer service is second to none and I honestly had the feeling that he really cares about being helpful. He gave me a ton of advice on my project and my results are spectacular!)

- Scott

Hi Scott! Talk about your blast from the past! Nice to hear from you. Thank you for your recollections.