Making Your Room Quiet

Posted by Hemos on Wednesday April 3, 2002 @05:11PM from the ssshh-SHUT-UP dept.

el_flynn writes "This may be a cure for those of you with loud computers, or perhaps those who spend lots of time in NOC rooms that generate lots of noise: NewScientist.com mentions about a "Silence Machine" that gets rid of unwanted noise. I want one to quiet down my neighbour's loud dogs. " These are also being tested in cars, to make the car quieter. I've got a pair of the headphones that the article alludes to - they make airplane travel much nicer, and having something like this to cancel machine noise would be excellent.

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This only works for low frequencies by Animats · 2002-04-03 17:54 · Score: 5, Informative

Noise-cancelling systems have been around for a while. Basically, they work only when the cancelling speaker is within a fraction of a wavelength of the listener. It's a speed of sound limitation. You can cancel 100Hz for several feet, but 1000Hz for only a few inches. That's why noise-cancelling headphones work well, but large-area systems don't.
You could build a system that cancels for a small target area from a distance, but it's going to produce twice the sound in other places.