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Old 11-03-2013, 11:05 AM   #1
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Lightbulb sound proofing a room

Soundproofing A Band Room
Using simple techniques and specialized products, you can block out even live rock ’n ’roll

By
Fernando Pages Ruiz





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I became interested in soundproofing at about the same time that my two teenage sons got into rock ’n’ roll. Heavy-metal music blasted from their bedrooms, and whenever their rock band rehearsed in the basement we could hear drums reverberate throughout the house. To turn the volume down, I included a basement practice room when we built our new house. Now when the band rehearses, we can still hear them — but it’s not loud enough to bother us.

To build the practice room, I used many of the same sound-attenuation products and construction techniques used to build professional recording studios. Since then, I’ve adopted these methods to silence laundry rooms, isolate attic furnaces, and make bedrooms quieter in the homes my company builds.
Understanding Sound

To build a quiet house, you have to understand how sound travels and how to stop it. Sound-absorbing materials — like carpet or acoustical tile — can help control resonance and make a room seem quieter, but they don’t necessarily stop sound from traveling to adjacent areas. To do that, you need to prevent sound transmission through both the air and the building’s structure. Noise from a television travels through air, while the knocking of hot-water pipes travels through the structure. Controlling each type of sound transmission requires its own set of products and methods.
Framing Strategies

Sound travels directly through studs and drywall by vibrating the entire wall assembly — much like a speaker — so that sounds hitting one side of the wall are reproduced on the other. Adding mass, more air space, and vibration-dampening materials to a wall assembly makes it quieter.

As a first step, we framed the partitions as double walls. Rather than staggering the studs and using common 2x6 plates — which would transmit sound — we used two separate 2x4 walls, floor to ceiling (see Figure 1). To further isolate the wall from the slab and the ceiling joists, I installed Integrity Gasket (Shadwell Co., 800/494-4148, integritygasket.com), a 1/8-inch-thick closed-cell self-adhesive PVC tape, under the sill plates and on top of the top plates.

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Figure 1. Parallel 2x4 partition walls (top) provide acoustic separation between rooms. To reduce sound transmission to the living space above, the author dropped separate 2x10 ceiling joists below the plane of the I-joist floor system. Note the green PVC gaskets separating the joists from the plates. Before drywall, the crew sealed potential airborne sound paths with caulk and spray foam (below left), then filled the cavities with mineral-wool insulation to further dampen air vibration (below right).

Ceiling. Framed floors, with their open joist bays, can transmit sounds throughout a structure; I-joist floors can make matters worse because the lightweight members don’t dampen sound as well as denser solid lumber joists.

The first floor of the house was framed with I-joists. Over the band room, I added separate 2x10 ceiling joists in the middle of every bay, notching them at the top plate to drop the ceiling plane below the bottom of the I-joists — which effectively isolated the band-room ceiling from the floor structure above (Figure 2). Again, I used gaskets between the joists and the top plates. The ceiling joists aren’t fastened to the plates, but are held in place by gravity; flat 2x4 blocks nailed between the joists keep them from tipping and eliminate a mechanical connection between the band room’s ceiling and the living room floor.

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Figure 2. Double stud walls and separate floor and ceiling joists help isolate the basement band room from the rest of the house framing, reducing structural sound transmission. A layer of mass-loaded vinyl underneath the room’s finished floor, walls, and ceiling dampens vibration and absorbs airborne sound energy.

For good measure, I also ran gasket material along the top edge of the first-floor I-joists instead of using construction adhesive; this created a permanently pliable cushion that eliminates squeaks and dampens noise transmission through the floor sheathing to the joists.

Dealing with airborne sound. To reduce airborne sound transmission, I kept penetrations for electrical boxes to a minimum, and avoided back-to-back receptacles in the double walls. I also avoided placing ductwork in the ceiling, where it could transmit sound through the joist bays. I carefully caulked all the wire penetrations through the studs and plates, then filled the stud and joist bays with 4-inch-thick mineral wool (Thermafiber, 888/834-2371, thermafiber.com), which is denser than standard fiberglass batt insulation.
Double Drywall

We first installed a layer of 1/2-inch drywall on the walls and ceiling of the band room, carefully taping and mudding every joint and making a special effort to seal every crack or penetration with compound or caulk. On top of the drywall, I installed a layer of Barricade mass-loaded vinyl (All Noise Control, 561/585-4703, allnoisecontrol.com; Figure 3).

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Figure 3. Mass-loaded vinyl fastened to the first layer of drywall deadens sound transmission through the walls and ceiling. On top, resilient channel is installed to receive the finish drywall layer.

This material is extremely dense: Even though it’s only 1/8 inch thick, it weighs a pound per square foot. But it’s also flexible — it comes in a 54-inch wide roll and can be pneumatically stapled in place. The combination of density and flexibility is ideal in a soundproofing material. The mass absorbs sound energy, while the flexibility dampens vibration in much the same way that a shock absorber dampens motion. Mass-loaded vinyl isn’t cheap — I paid a little less than $2 per square foot — but it’s very effective in an otherwise well-sealed acoustical wall assembly.

On top of the vinyl we installed standard resilient channel, then a finish layer of 5/8-inch drywall.
Doors and Windows

An effective way to reduce sound transmission around doors (and windows) is to seal gaps between the frames and the rough openings with either acoustic caulk or low-expansion polyurethane foam. The double walls allowed me to install a two-door entry into the band room (Figure 4).

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Figure 4. A pair of 1 3/4-inch solid-core doors — air-sealed as carefully as exterior doors — create a sound-defeating air lock between the practice room and the rest of the basement.

I used solid-core 13/4-inch-thick door slabs for their extra mass and installed air-sealing thresholds, caulked to the floor, under both doors. I also sealed the gap between the jamb and framing with QuietSeal butyl acoustic caulk (Quiet Solution, 800/797-8159, quietsolution.com) and caulked the stops to the jambs and the casing to the drywall. Finally, I added self-adhesive compressible EPDM weatherstripping around the stops.
The Results

Framing and soundproofing the 11-foot-by-17-foot room cost nearly $15,000, but this was a small price to pay for the luxury of shutting the door and going to bed even when the band jams ’til dawn.
Fernando Pags Ruiz is a general contractor in Lincoln, Neb.













http://www.jlconline.com/acoustics/s...day=2013-10-31
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Old 11-03-2013, 11:41 AM   #2
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Beranek's "Acoustics" is the industry standard book on all this, and gives the reasons and the math for how to do just about anything regarding sound and vibration.
Isolation and absorption are separately important - and absorption is not done as well by most materials as people think. Egg-crate shaped foam rubber == 0, for example, it's 100% elastic and changes zero sound into heat.

I've been using the tech and ideas from that book for a lifetime - the rules haven't changed at all.
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Old 11-03-2013, 11:57 AM   #3
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I am always considering ideas to lessen the road noise per my house.
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Old 11-05-2013, 03:49 PM   #4
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How about so no one can hear my victims scream!
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Old 11-06-2013, 08:53 AM   #5
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Rule of thumb - it's a lot easier to get rid of high frequencies than low. Screams - easy. Rumble - very hard. Low stuff might even just be seismic - shaking ground - very hard to isolate from.
Beranek has it all.

It has to do with the wavelength at the speed of sound in the material - about 1130 ft/sec in air. You need to be working with at least large fractions of a wavelength to do much. At high frequencies, the wavelengths are short, but at 10's of Hz - very long.
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Old 11-06-2013, 09:08 AM   #6
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Originally Posted by 11C1P View Post:
How about so no one can hear my victims scream!
Not funny. There are some really sick and evil people out there who are thinking the same thing. I would urge PMBug to flush this thread.
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Old 11-06-2013, 09:18 AM   #7
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I reckon theres a lot of money to be made by using anti-noise to cancel noise.

If lorries, aeroplanes, motocross bikes and all those noisy things that piss people off could generate an anti-noise pulse using a sound generating system, they could possibly (?) make the world a better place for the undeaf.

I suspect however that if it was that simple it would already be happening



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Old 11-06-2013, 09:31 AM   #8
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"I reckon theres a lot of money to be made by using anti-noise to cancel noise."

There is, but it doesn't work that well for a lot of important cases. Your anti-noise has to have exactly the same spectra AND PHASE at the place you want it to cancel out. Which will basically only be in one tiny spot (for high frequencies) unless either the anti-noise is co-located (within a fraction of an inch for high frequencies) with the noise source, or right at the ear, with the noise to be canceled being measured very close by (noise canceling headphones). It works for headphones (kinda) only because you can measure close by, but still not hear your own anti-noise, so you get a clean signal to cancel - it's the isolation from inside to outside the earphone cup that provides that in this case.

I did a lot of development on that, personally, and yes, made money doing it. It's real non-trivial, especially when things make a LOT more noise than an audio system (your anti-noise generator) can - think big engine or similar.

The Army even spent a lot of bucks trying to cut vibration in HMMVs with piezo-activator motor mounts for example. Took kilowatts of power to help even a little bit.

The trouble is, the ear is logarithmic in response. To be half as loud, you have to be at 1/10th of noise power. Cancellation is quite delicate if you need tens of times that, and you do. You can actually hear an eardrum motion the size of the width of a hydrogen atom if its quiet enough, yet live through 125 db (close to a metal-rock band) or 140 (jet engine on the tarmac) or 160db - guns or jet engines up close. While talking is 60-70db right next to you - loud enough.

Every 10 db (which is a half or doubling of perceived sound energy) is 10x power...cancellation is tricky stuff - you have to be very accurate to reduce noise 40 db - which isn't enough for most cases (that's 1% accurate in power and phase at every frequency, cumulative error total).

But in general, noise issues are, yes, a big deal, and a source of a lot of skull sweat when planning anything decent sized like a factory, or a scientific lab where vibration from say, a vacuum pump totally destroys say, an electron microscope's resolution.
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Old 11-06-2013, 11:54 AM   #9
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Ha thought you woulda done some thinking on the noise thing Fusor.

What about a micro hearing aid type of device that does it in your ear ?

Be better than those ear plugs for sleeping with snoring companions (-:
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Old 11-06-2013, 03:34 PM   #10
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Originally Posted by Aubuy View Post:
Not funny. There are some really sick and evil people out there who are thinking the same thing. I would urge PMBug to flush this thread.

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Old 11-06-2013, 06:04 PM   #11
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I was in a sound-proof recording studio once that was also full of sound-absorption materials on the inside. It was so quiet, I could hear my own blood pumping through my ears. I kid you not.
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Old 11-06-2013, 06:10 PM   #12
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Originally Posted by DCFusor View Post:

There is, but it doesn't work that well for a lot of important cases. Your anti-noise has to have exactly the same spectra AND PHASE at the place you want it to cancel out. Which will basically only be in one tiny spot (for high frequencies) unless either the anti-noise is co-located (within a fraction of an inch for high frequencies) with the noise source, or right at the ear, with the noise to be canceled being measured very close by (noise canceling headphones). It works for headphones (kinda) only because you can measure close by, but still not hear your own anti-noise, so you get a clean signal to cancel - it's the isolation from inside to outside the earphone cup that provides that in this case.
I bought noise-canceling headphones for our last trip to the US. They're not perfect, but definitely worth the money. They worked a lot better than I thought they would.
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