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Area wide Active Noise Suppression for Consumers?

This question is directed to any electronics buffs or audiophiles in attendance.

Are there any products on the market, or have you ever seen plans, for active noise suppression that operates on a room wide scale? IE, I am imagining something (such as one of these "speaker" gadgets that use a wall for a resonance plate) that could be attached to a wall to deaden sound exchange.

I am specifically talking only about techniques that sample noise and produce a 180 degree out of phase sound signal that effectively cancels the noise. This technology is used in industrial environments and in the aviation industry and supposedly works best with low frequency sounds. I've scoured Google (groups and web) but have not seen specifics in this area.

And I am not talking about drowning out the noise with white or pink noise, nor am I talking about noise suppression headphones. I have experimented with a fan in the office and I keep a jazz Realplayer session going constantly for background. I get tired of a high background noise.

My "problem" is a barber that I have for a next door neighbor in my office complex, who tends to have groups of elderly hard of hearing men guffawing constantly in his room.

I've already installed a better door in the office where the sound comes through, so aside from noise suppression my other choices are: an "airlock" (closed hallway built inside my office); or, move.

What little research I've done indicates that this is really a DSP type problem and is not amenable to a homebrew solution, although I would be delighted to hear about such a solution.

Thanks.

Goddard Bolt
Tuesday, September 16, 2003

No there is no such thing. If someone succeeds in this he will be an instant billionaire.

Just me (Sir to you)
Tuesday, September 16, 2003

I work part time at a research lab, and they have this thing that sort of does what you describe. It is a plexiglass dome that hangs from the ceiling, and if you are sitting under the dome, it cancels out the noise around you. It was produced by a small firm specializing in acoustics but I think it was a one-off project. I believe the price was about $10,000.

rz
Tuesday, September 16, 2003

I saw one of these on "Get Smart".

njkayaker
Tuesday, September 16, 2003

If anyone does this sort of thing I guess it would be Boise. They make really execellent NR headsets for light aviation, but they are designed to reduce the background roar of the engine without interfering with speech.

David Roper
Tuesday, September 16, 2003

This was invented by Arthur C. Clarke in one  of the stories in Tales from the "White Hart"

Seriously, I have a pair of Aiwa noise reduction headphones (+-$50) that work great on airplanes.

pdq
Tuesday, September 16, 2003

It's much harder to do that to supress noise over a large area than it is to do a local area, either under the plex or with headphones.  I think trying to find an active noise supressor is a jynx, untill audio technology gets much better.

You are right about the white noise not being the answer.  Hearing only the sounds you want is much better for your stress level.  Things like white noise and humming noises will eventually grate on your subconscious mind.

Your best solution is generally some sort of sound-deadening material between you and the other office.  Because it's an interior wall, there's probably just a sheetrock and wood framing between you and the other office.  So if you are prepared to give up a few inches, you want to set up a second wall, that is insulated.  This will work much better than trying to put a hallway in.

On the cheap, you can just use good old pink insulation.  Or, you can get materials that will offer more isolation than pink insulation per inch of material. 

Check out http://www.auralex.com/c_sound_isolation/c_sound_isolation.asp for what I'm talking about -- their Sheetblock and Mineral Fiber insulation would be most useful to you.

Depending on how concerned you are about the appearence, you might not even need to get any construction workers in.

Flamebait Sr.
Tuesday, September 16, 2003

The short story it was introduced in was "Silence, Please" and detailed all of the social disruptions that instant silence could cause those trying to push their view on others.  A very entertaining read.

Unfocused Focused
Tuesday, September 16, 2003

The original poster could also consider talking to his landlord about pulling open the existing wall to install sound-dampening material in it.  This is especially true if the O.P. was willing to share some or all of the cost.  A trip to a Home Depot (or local equivalent) is sure to net someone who can enumerate the different types of available material and how well they each insulate noise.

The Pedant, Brent P. Newhall
Tuesday, September 16, 2003

What about that... I think radio shack released it, sort of a laser-beam of audio... I'll have to dig up the article. It could make you sound like you were in a rain forest or something, even though people 2 feet away couldn't hear it.

Then combine that with some sort of localized hyper paraboloc microphones with the proper phase correction... invert the signal, boost, run some processing on it...

Could work, but only over a small area.

Tried those noise cancelling headphones in the Sony store. They were pretty neat. I found some discussion about this in a pro audio group, I can dig it up if anyone is really interested.

www.marktaw.com
Tuesday, September 16, 2003

Active noise cancellation for large areas is (effectively) impossible to accomplish with current technologies. If you have noise problems, I would recommend contacting a noise consultant in your area.

Herb Singleton
Tuesday, September 16, 2003

i think marktaw is referring to:

http://www.holosonics.com

we have one of those at the lab too, it is pretty sweet.

there is another similar device, but the holosonics one is better.

rz
Tuesday, September 16, 2003

"I work part time at a research lab, and they have this thing that sort of does what you describe. It is a plexiglass dome that hangs from the ceiling, and if you are sitting under the dome, it cancels out the noise around you. It was produced by a small firm specializing in acoustics but I think it was a one-off project. I believe the price was about $10,000. "

They have a bunch of these hanging from the roof in the sydney operah house main concert hall.

Chris
Tuesday, September 16, 2003

Yeah, I saw one of those domes years ago on TV.  I think it was on "Get Smart".

timid troglodyte
Tuesday, September 16, 2003

Incidentally, pulling off the sheetrock, putting insulation in place, and mounting it again will

...be a colossal waste of money.

Because you'll still have a sound short through the wall. The sheetrock in the barbershop is a diaphragm that is actuated by the noise in the barbershop. As it vibrates, it moves the studs (that are nailed to it). As the studs move, they vibrate the sheetrock on the *other* side, making the original poster's wall into a big ol' speaker.

Putting insulation in the spaces between will dampen the sound some, but not much.

The *best* thing to do, if we're dreaming, would be to pull down the sheetrock, put new studs in between the existing studs, put your insulation in the remaining gaps (tough, since you now have a nonstandard gap size), put noise dampening foam on the faces of the existing studs, and put the sheetrock up again, mounting it to the new studs.

Should kill 99% of the noise.

Philo 

Philo
Wednesday, September 17, 2003

http://www.acoustics101.com/

http://www.auralexuniversity.com/NeighborsWMA.html

This second link has mp3's of a sound source as heard from behind several different walls... one layer of sheetrock, etc. etc.

Double paned glass works better than single paned glass, and even better is two tightly sealed panes of glass at an angle from each other: | / so as to prevent vibrations from building up between them.

The door also needs to be pretty much air tight.

Another thing you can do is deaden the space inside your office area so that once the sounds get in from the outside, they don't bounce off the walls and reach your ears.

It all depends on how much time, money & effort you're willing to put into this project.

Or just make friends with the barber next door & then the sounds coming in will have meaning and won't seem like random noise. "That Alfonzo is such a cut up. Eduardo should really get that cough looked at."

Mark T A W .com
Wednesday, September 17, 2003

"Another thing you can do is deaden the space inside your office area so that once the sounds get in from the outside, they don't bounce off the walls and reach your ears."

And in the hallway between your offices. A few strategically placed plants or velvet wall hangings.....

Mark T A W .com
Wednesday, September 17, 2003

Really what you need to do is identify *where* the sound is coming from. Is it through the wall or through the doors? You can't effectively address this until you know. Maybe it's coming through the air ducts. Maybe the wall doesn't reach the ceiling and it's coming through the plenum (the area above the ceiling where all the wiring & ducting goes).

Mark T A W .com
Wednesday, September 17, 2003

Regarding: Are there any products on the market, or have you ever seen plans, for active noise suppression that operates on a room wide scale?

I have been searching for such a thing, but failed to find anything. I then resorted to finding something I can put on my head. I tried those USD$80 ones sold in BestBuy, they don't work. I have heard reviews for USD$800 consumer editions of pilot ear muffs, they only work for planes (and I can't afford them). Mainly I wanted to silence the following appliances: Keyboard, Mouse, Computer fans, hard drives, electric fans, and air conditioners.

The best solutions I have found so far are pretty low tech: Quality parts, thick padded wooden cabinets/containers works wonders according to some internet articles.

I work in a really noisy environment (see you across me desks and cubicles) and usually I have been able to work well as long as my coworkers respect everyone's need to quiet time.

Li-fan Chen
Thursday, September 18, 2003

Cheap sound insulation are egg-boxes. Look funky after you've painted them as well.

Most sound comes through windows; air-ducts can also carry it as well. Check those out first.

I suspect the problem lies in the interior wall - what's it made of? As somebody suggested it is possible it is acting as a giant speaker.

I have lived in various apartments in Saudi, and in one of them all the neighbours  had at least half a dozen kids (with the exception of the 13 Philipino garment workers they crowded into the two bedroom apartement opposite).

I never once heard a sound from any of the neighbours. I presume the reason was thidk masonry walls.

Stephen Jones
Thursday, September 18, 2003

Check out www.quietsolution.com  This site has several PDFs that describe techniques for sound proofing building construction.  They are a manufacturer of building material, so of course they emphasize use of their products, but they do have a lot of general information.

This doesn't answer the question in the OP.  No, I don't know of any such product.  Active noise suppression over a wide area is a different problem from small area noise suppression achieved by noise suppression headphones.  Consider that the speed of sound is about 350M/s.  Then the wavelength of a 1000Hz tone is 0.35 meters.  In order to achieve sound cancellation, the original noise source and the generated cancelling signal have to be 180 degrees out of phase at both ears.  As you move about a room the path difference from your ears to the two sources changes.  An active noise cancelling system would have to keep track of where you are and adjust accordingly.

Constructing a quiet room sounds like it should be easier and cheaper.  Either discuss the issue with your landloard and come up with some building modifications, or move.

mackinac
Saturday, September 20, 2003

I'm looking for something similar. We have video conferencing cubicles in our office and are looking for a device that will help deaden the sound from cubicle to cubicle. Yeah, we could use insulation and matting, but we are moving soon and wanted something we could take with us easily.

I don't see why you couldn't just make a larger speaker version of noise cancelling headphones, with a mic to pick up the ambient sound, and an omnidirectional speaker to emit the cancel wave to "kill" the sound travelling through the area around the speaker.

Also noticed something else, maybe one of you can explain it. While over at my friend's house I noticed him playing with a laser temperature reader. You just point it at the wall, click and it tells you the surface temperature of the wall. I tried to see if it would pick up my ear temprature or if the surface was too distorted. While holding it up to my ear and without pushing the button I noticed all sound was cancelled around that ear. The device has no on/off switch, this effect was always present and others experienced it too. It was sound dampening of some type, but there was no white noise involved in a normally audible range. Laser power source dampening the sound?

Kurt
Monday, March 22, 2004

I am looking for something to cancel the sound from the highway in front of the house.  IE. interrupt the tire/engine/exhaust noise and cancel it out with something else.  It needs to "protect" an acre or so.

Don Koski
Wednesday, March 31, 2004

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