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By Grindstone
I'm trying to find out if anyone has invented a portable negative noise generator for in the house. I'd love a small, portable machine that analyzes a noise source and then puts out a negative wave to counter it. We could put them on/in fridges and washing machines and other noisy items in the home to get those annoying sounds out of our lives.

Reward: A calm, peacefull existance.
By treadair
Don't remember if it was portable or not but there was an article in New Scientist awhile back about something called a 'Silence Machine' that did this. A google search should give you more details.
By kessmann1
I saw such a device demonstrated on TV by an inventor nearly
25 years ago. The device automatically sensed the frequencies of the offending noise and then put out the exact opposite frequencies
to cancel that noise. It was demonstrated on lawn mowers and
obnoxious sounding tree shredding machines. The result was
complete silence. I don't know why this idea never got to market.
It seems to me that such devices should be mandatory under
some noise pollution ordinance. It could be extended to other applications such as barking dogs and noisy airliner takeoffs and landings.
By kessmann1
My previous post has some inaccuracies. First, the TV show was more than 25 years ago. I watched it in black and white before
there were color broadcasts. Second, the device put out the same
frequency as the offending source but was shifted by 180 degrees
on the sinusoidal scale.

I have investigated the Silence Machine mentioned above. It seems
very complex with microphones and a powerful computer. Nowhere
did I see mention of an actual installation as of yet.

The device I referred to above was very simple. It was about the size of a cell phone and could be attached to the offending machine
(i.e. portable). I wonder if a patent exists in the U.S. Patent Office
By graham
I'm pretty sure that Bose manufactures headphones that have that functionality.
By kessmann1
Yes, Bose does. But why should I have to wear uncomfortable ear phones to mask out unnecessary and blatant noise generated by inconsiderate others?
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By Michael D. Grissom
As stated in other ways above, active and passive source noise cancellation has been around for a very long time. There are many past articles in Popular Science/Mechanics on the subject. It has also been successfully installed on concept cars and aircraft to silence interior cabin noises. This technology can silence just about anything.

The trick is to make it cheap enough for consumers to buy and, so far, nobody (as far as I know) has succeeded in doing that. It always seems to be less expensive to make the noise creating device quieter.

However, if you 'do it yourself' it's really quite simple and inexpensive. Continuously record the noise from the device (microphone) , invert that noise 180 degrees (one transistor), amplify it (audio amplifier), and feed it to speaker(s) pointed at the noise source (anywhere between you and the source) at a speaker output level equal to the noise source and, BINGO, you have your silence.

This is exactly how noise canceling head phones and microphones work only with bigger speakers between you and the noise source.

Make one that's inexpensive enough to be marketable and you'll make a fortune! ;-D
By kessmann1
Let's not get carried away. Consider:

"The silence could be deafining"


"The silence could kill us"
By Jack Nobbz
This is the second idea I've seen on this site that isn't really bloody stupid. This is pretty good.

In terms of how it'd work, you're right. Active noise cancellation (producing an amplitude-inverted wave to match the source and destructively interfere with it) would be used. However, the active noise cancellation would have to be placed as close to the source as possible, otherwise some of the inverted signal would be unlikely to be in phase with the source signal, and you'd end up creating a lot more noise than there was originally.

Overall, this idea is a cool one, though, I reckon on certain devices it could well be done. Nice one!
By mikem
Active noise cancellation is pretty location specific. If you have a microphone next to a noise cancelling speaker, it will work great next to the microphone, but it might be really loud a few feet away. A solution may be to set up a few of them throughout the room, but you would have to show they wouldn't fight with each other too much.
By Rishi
mikem wrote:Active noise cancellation is pretty location specific.

That is the crux of the problem. For it to be effective to the person hearing the noise, the whole caboodle has to go with the person. In addition, noise from various sources will have their own individual signatures and directions. This may need a fairly hefty computer to handle the analysis and generation of the 180 degree out of phase signal. More will be needed to deliver it in the right direction

You may silence the neighbour's lawn mower but continue to hear your own husband's/wife's nagging. Also the spill over of everyone's Noise Terminator noise may itself be deafening. A well designed hypoallergenic, soft, sound deadening substance for ear plugs may be a cheaper answer.

This can be delivered like tooth paste to set in the ear when exposed to air. Unplug to hear sweet nothings (before they transform to the aforesaid nagging).


By Rishi
The second rishi in the previous post is 180 degree out of phase.
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By Greenearthman
hi, i have a very simple invention for this i use everyday, its called a fan, i use a fan to block out the tv in the next room, a baby crying, etc. if im not hot i just point the fan towards the closet or wall, let me know what you think.
By Rishi
elenos wrote:What needs inventing is an inexpensive device, like a walkman, that you can hear pink noise that drown out others through small earphones. Perhaps something like that may do something to hearing after a while, I don't know, but I've never seen one. They have noise reducing headphones for rifle ranges and noisy jobs, but none are dynamic in the way they reduce sound.

Bose systems already market this noise canclling headphones in USA.


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