I should postcript this by saying that soundboard now no longer requires a metal liner
in the middle as a carrier to the acoustic polymer, and is just as simple as working
with regular drywall, except more expensive, AND you need the proper acoutic caulk
and installation technique. The brand you want to research is Quiet Rock. Around
80 to a hundred bucks a sheet, depending. The same technology also exists for
laminated plywoods, which can be used for the floor or whatever.
Noise-canceling headphones suppress highly repetitive ambient sound, such as the vibrations produced by machines. They are great if you're riding in an airplane or helicopter - or in a car, or sitting next to an air conditioner.
They detect a repeating wave form (like from a lawn mower engine), and apply another identical wave, 180 degrees out of phase. The resulting sum, is silence. They literally "cancel-out" the offending signal.
This approach doesn't work as well for music or speech, which is (compared to machine noise) irregular by nature.
I think that sound proofing a large darkroom like that would be difficult to achieve and extremely expensive. For that kind of money you must be able to find wireless headphones on a network to share sound with others. You could hook the headphones up with a wireless headset microphone and talk back and forth while toggling the music for the thousands of dollars you will save.
I did a lot of research on the soundproofing problem when I built my studio next to my wife's studio. We both play music, but not always the same music, and found it necessary to isolate. There is a website online that is the exact format as large format photography forum, which deals with all the issues surrounding this subject (I'll try to remember the site name).
In one word, the answer is air. You can talk about lead foil, double sheet rock, urethane, etc, till the cows come home, but air is what you need. Build two walls with an airspace in between. Or you can build one thick 2X6 wall and split the 2X6 header and foot right down the middle and separate them enough so they don't touch and then stagger the 2X4's to accommodate the two outer sheet rocked walls. That will take care of sound escaping from an enclosure. The urethanes, soft surfaces, and ceiling "clouds" will temper the actual space that contains the music source, but the air space is what you need for containment. There is one other idea that is slightly useful, and that is to double sheet rock on both sides of the wall, but use regularly spaced globs of silicone to "float" the second layer of rock. Use fewer screws so as not to allow too much transmission of sound from one layer to the other - in other words, create yet another micro space of air between the two layers.
Here is the website:
http://homerecording.com/bbs/forumdisplay.php?f=20
Room within a room, I recieved a PM that basically said the same thing from someone I respect on this site.
It sounds like I am asking for a lot of woopass if I proceed with this size of project. I can only dream of the day where I can move the Lab up North and just surround the darkroom with acres of land.
Thanks for all the replies .
Originally Posted by Rob Vinnedge
There's an entire profession called acoustic engineering. You can make life hard for
yourself if you want double walls and so forth and it will probably work, but you
will waste and bunch of money, time, and lose square footage when they are actually
much more efficient ways of doing this, even if the materials cost a little more up
front. There is all kinds of hard data on this including cost anyalysis and sone ratings.
It's very routine and even required in building codes for high-end spaces around
this part of the world. Just depends whether or not you can sacrifice the square
footage to build a double wall, or if you need a more modern answer.
One item I didn't see mentioned is that double walls by themselves are not optimized until the the two walls are tuned to different resonant frequencies.
Any material will vibrate at a preferred frequency when activated by impact or sound energy. Think of a bell or a tripod. If one wall responds to one frequency, and it's neighbor responds to a different (and not a multiple) frequency, the two walls will tend to "ignore" each other and transmit a disproportionately lower amount of energy throught the whole assembly. It has to do with properties like stiffness and mass.
Getting all this right, or finding useful alternate schemes takes the expertise suggested by Drew Wiley. It gets pretty technical rather fast.
CG,
You may well be right about optimization of double walls. However, I built my two 2"X4" walls 2" apart and sheet rocked three of the four sides with 5/8" sheet rock and cannot hear a thing from the other side. Could I have just been lucky, or is it possible that the second layer of sheet rock on one of the walls could have broken the transmission?
Bob,
Get an iPod and spare your neighbors. You can play it as loud as you like and the only thing to suffer will be your hearing and brain.
Sandy King
Hi, I actually am an acoustical engineer and I work on these design situations daily on everything from multi-family residential buildings, to industrial power plants, to concert halls. It is hard to give you any accurate advice as I haven't seen your room or your construction, but what I can tell you is that reducing the sound transmission to a level so as not to disturb your neighbors is an extremely challenging problem and will likely require a huge effort.
Sound absorption materials on the walls is generally effective at mid to high frequencies unless you have significant thickness or provide an airspace to back the material, and even then it will just reduce the reverb level increase which is not that significant.
A better solution is to provide a double-stud wall (two independent rows of studs) with an uneven number of drywall layers on opposite sides, and batt insulation in the cavities. Do not place drywall layers at the inner side of the studs as all you do is reduce the airspace and low-frequency sound insulation performance. If you cannot fit a second stud track, you can make a compromise with something like Kinetics Noise IsoMax, or RCSD resilient channels, but these are difficult to install and require technical expertise. A mistake with these like driving screws into the studs renders them mostly useless.
These walls need to either be full-height and sealed to the deck above and floor, or you need a multiple layer drop ceiling to close the acoustical envelope. Your skylight and any lightweight drop ceiling are going to be a problem. You will also get sound propagation down exhaust and supply ducts if you do not treat that as well with sound boots or plenums. Don't waste money on QuietRock. If you look at their acoustical lab tests, you will see that the performance does not apply to this situation. You will need to properly seal gaps, cracks, etc. and pay attention to intersections at floor-wall-ceiling. Do you need to maintain a fire-rating on your walls? Probably yes if you have adjacent neighbors. This will send you to an architect and building permit.
I see this time and time and time again, and I rarely see this pan out to anything less than thousands and thousands of dollars by the time it's done. Without an architect and acoustical consultant, you're likely to overlook things too like penetrations at conduits, piping, junction boxes. You will be able to buy your whole staff a pair of cordless headphones for less money, and they are guaranteed to work, whereas a home-brew sound insulation project is not.
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