How far has sound cancellation technology come, for use in a room area? For example, for a bedroom?
I need some sound cancellation in the bedroom due to street noises outside while I'm trying to sleep.
I know they have it inside closed headsets for pilots etc, but is the technology viable yet for a closed room sized area like a bedroom?
-- A Voice Of Freedom in the United States of America
No, and (for all practical purposes) it never will be. Headphone devices 'muffle' the higher frequecies while 'cancelling' the lower ones. But this only works with headphones.
-- Luhan Monat (luhanis 'at' yahoo 'dot' com) "The future is not what it used to be..." http://members.cox.net/berniekm
I have the answer you seek, , but I don't answer questions that are posted to the wrong places. You posted to:
sci.electronics.misc .misc newsgroups are for posts that don't fit anyehere else. This post does fit somewhere else, so it shouldn't be posted to sci.electronics.misc.
sci.electronics.equipment Possibly OK, depending on what you are asking for. If you want an existing piece of equipment, your post belongs in sci.electronics.equipment but not in sci.electronics.design. If you want to design something or have something designed, your post belongs in sci.electronics.design but not in sci.electronics.equipment.
misc.industry.electronics.marketplace .marketplace newsgroups are for posts advertising things for sale. You aren't selling anything, so you post does not belong in misc.industry.electronics.marketplace
sci.electronics.design Possibly OK, depending on what you are asking for. If you want an existing piece of equipment, your post belongs in sci.electronics.equipment but not in sci.electronics.design. If you want to design something or have something designed, your post belongs in sci.electronics.design but not in sci.electronics.equipment.
Don't be such an ass. If you really know, then give the answer, otherwise bug off. (i am answereing him dierctly, if you look on these NGs)
Voice of freedom wrote:
Systems have been built in large halls to get rid of un-wanted echos as well as enhance the on-stage performance. I understand that some of these systems are dynamic, so that sounds from one part of the stage are processed differently than others. That said, it would seem to be very possible to achieve at least reasonably acceptable results. If you do not mind experimenting, you might see if you can get a surplus headset that has the cancelling technology, along with as much technical info as possible. One or two microphones placed outside - say one mounted on cushions so that it only picks up sounds in the air, and the other mounted near the base of the wall nearest to the traffic so that it pickups sounds by "conduction" from the wall (and not by air). These mikes are the "reference" noise pickups; the waveforms would be processed before feeding to speakers inside the house/bedroom. Mostly the lower frequencies are the culprit, so some of the processing would appear to be possible via filtering. The basic idea is that the sounds from the indoor speakers are "EQ" in both amplitude and phase across the spectrum of interest - to cancel the sound that is transmitted via air thru windows and walls, and cancel sound conducted via wall and earth movements (truck rolls by). The "air" reference is processed for the first part, and the "conducted" reference is processed for the second part.
I use the word "processed" on purpose, as a DSP might be necessary to achieve optimum results. The surplus noise cancelling headphones may or may not have a DSP, depending on how new it is; one would try using two - one for each of the "channels" i mentioned.
If you have some kind of network with contacts to sound engineers in opera houses, sound stages, etc, do not hesitate to ask if any "exotic" technology is used; and for help.
The limitations are not in the technology. It is just a physics thing
- you can't cancel sound in volumes larger than a fairly small fraction of a wavelength.
Not now, not ever.
dPearce Consulting
There are windows you can buy with a film inside that muffle sound or you can create your own 'storm' window with heat insulation film, a frame and another layer of glass or polycarbonate. Ear plugs are another posibility? Not electronics but then, they work.
Voice of freedom wrote:
I use earplugs with great succes..
-- - René
For
Simpler, more effective, and most importantly, currently available:
Please, I'd like some refferences on that. The tests I've conducted (two
4" speakers 1kHz in a Y-shaped pipe) suggest that it can cancel _pretty_ loud sounds. I don't know what signal level I ran at, but it was at least hearable 30m from the source. When I fed the speakers with opposite waveforms, they canceled out, and only a slight hum could be heard. I guess this hum was the vibrations in the mount for the speakers.
-- MVH, Vidar www.bitsex.net
This experiment has nothing to do with cancellation in a room. Take the speakers out of the pipe and try again. Use broadband noise as your sound, and see what you can achieve by way of cancellation. Mainly find out how far apart you can place the speakers and still achieve useful results.
dPearce Consulting
Well, I can't see how not. If you manage to place them according to the noise, you should get the same effect, if using a DSP that calculates the waveform, and timing. Mercedes used this on some of their cars to cancel out noise, and many planes use it...
-- MVH, Vidar www.bitsex.net
Do the experiment. You will find out why. The stuff in cars and planes works - barely - for two reasons.
Pearce Consulting
I sold and installed the Headsets, Inc. Active Noise Reduction (ANR) kits to pilots for a while back in the mid nineties. Kept up with the advances back then. If I recall correctly, Bose Laboratories in Boston was experimenting with "whole aircraft cabin" ANR systems, and that some Business Aircraft manufacturers were offering Bose's ANR option to anyone who could afford it. The option was expensive, requiring a number of well placed speakers, a fair amount of electronics, and extracting some useful load. For reference, refer to indices of the SAE publication "Aerospace" from the mid to late nineties. I think I also recall that someone was building similar ANR systems for OTR Trucks.
Recollections aside, in my opinion, ANR equipped headsets were, and are a real plus while flying in general aviation aircraft. Most systems I tried cancelled much of the lower frequency engine and exhaust noise, and certain components of slipstream noise. The design and shell of the headset earcups knock down much of the higher frequency components. All of which makes for a more relaxing, less tensing flight. A bedroom sized system might work similarly well for lower frequencies, but I doubt there would be much protection from higher frequency components such as sirens, plant whistles, and the like. Just like the earcup shells on a headset, one would probably need to super-insulate the walls of the bedroom. One problem which was dominant with all systems was a "hiss", almost like "white noise". This could be a bigger problem on a room or cabin sized ANR system.
Hope that helps to answer the original question. Aloha, Dave
Your name is Rube Goldberg?
-- A Voice Of Freedom in the United States of America
Yes, I've heard that some experimenters have come pretty close to being able to do very simple sound cancellation in a room area, without headphones, but not close enought to produce a perfect product to sell. High speed DSP was mentioned.
-- A Voice Of Freedom in the United States of America
outside
I already have double windows, which helps some, but the place across the street is running some kind of home shop business and fills up their dumpsters a couple of times a week, then calls for pickups. The garbage truck is a big diesel rumbling thing and that wakes me up, right through the walls etc.
-- A Voice Of Freedom in the United States of America
available:
Unless you sleep during the day, check the Noise abatement regulations and file a complaint.
If you sleep during the day Move! It's cheaper.
The next technical step would be a "room within a room" which is of course a large cost in labor and building materials. It would need to be built on a floating floor, with the walls and ceiling built on top of it without touching the existing walls and ceiling. Read F. Alton Everest's "Master Handbook of Acoustics" if you consider doing this.
Do as Clarence suggested and look for some local noise ordnances they might be violating, in addition to running a business in a residential area which might also go against some ordnance, but at least be a good neighbor, explain the problem to them and give them a chance to fix it before turning them in for anything.
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"Dave Fase" writes: ...
...
One quick question, having tried three brands of noise cancelling headsets, all three seem to do a good job at reducing low frequency noise like the roar and rumble inside city busses, engine noise, etc. But that just brings out the conversations that would otherwise be buried by the roar.
Strictly dealing with headsets for this question, is not also cancelling voice/music by design, by limitations of physics, by limitations of processing power, by limitations of battery power or by cost of components?
On related notes, but not wanting to derail answers to my question, perhaps a decade ago I was sitting in a class where the prof claimed that he had direct knowledge that the Cadillac NorthStar was named NorthStar because N S recognized that they had built Noise Suppression and noise cancellation into this car line. I was interested in this and contacted Cadillac about this at the time. They responded that this was not the case. We never could resolve this contradiction.
Since that time we have seen advertisements by the companies selling trucks to the public, describing how much work they put into making the sound of their trucks make it clear that the owner has really really large male equipment.
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