Half a croissant, on a plate, with a sign in front of it saying '50c'
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Noise triangulator

Find the direction and distance to any noise around your house
  (+7, -1)
(+7, -1)
  [vote for,

"Shh, listen!" It's 2 a.m. and you thought you heard a noise outside. Now you're staring out the back door of your rural home and don't hear anything. Wouldn't it be nice to run to the computer screen to see where the noise came from? You could then go immediately to that spot and check out the problem.

The idea is simple -- you lay out three microphones around your property in a triangular fashion about 20 to 100 ft apart. These microphones connect to your computer. A software program monitors the noise pattern, and any sound significantly above the background noise is triangulated to determine the distance and direction. This is then plotted on an azran-type grid on your computer screen. More inclined users would be able to make their own background maps and load those in. New noises are plotted in yellow and older noises are plotted on the screen using different shades of blue and gray.

This probably wouldn't work in urban areas or near heavily-travelled roads due to high background noise levels, but for all other people it would be an incredibly useful device. ESPECIALLY in rural and wooded areas! Any unusual noise, footsteps on dry leaves, gunshots, firecrackers, shouting, voices, parties, wild animals, etc, would be instantly mapped out and you'd know where it's coming from. You could even see the path of a wild animal or an intruder. The price of the microphones and computer interface would be insanely low (less than $40) so someone could conceivably make a killing off such a device. Unfortunately the market is still a vacuum.

I know one company is selling such a device to pinpoint gunshots in gang-infested areas, however the price tag is extremely high and the market is completely different.

If anyone develops such a device, let me know! We'd be the first customers. We're always interested in unusual noises on or near our 10-acre rural property.

timvasquez, Apr 16 2001

Sniper version. http://www.halfbake...idea/Find_20Snipers
As you say, a very different market. [jutta, Apr 16 2001]

ShotSpotter http://www.ncjrs.or...j/grants/180112.pdf
Tested in 2000 [csea, Nov 23 2005]


       You watched "Friday The 13th" ON Friday the 13th, didn't you?
thumbwax, Apr 16 2001

       There are motion detectors that turn on lights and sprinkler systems (to discourage animals). There's a gadget that looks like a pistol with a dish antenna and earphones that you could stand out in the dark with and possibly locate the direction of a sound.   

       Alternately, there are sleeping pills and ear plugs.   

       Also, see Bump-in-the-night Program.
melanerpes, Apr 17 2001

       Good idea. Actually, there are techniques to get even more information.   

       Once you find the position of the sound, you can add up their signals (delayed to match the position of the object). The ambient noise mostly cancels itself out, and you get something like 9 times the signal strength (w/ 3 microphones). This works even better with more microphones. The software to do this could be fairly complicated, since it'd have to account for reflections. This could be minimized by having more microphones, or some clever programming. The one piece of hardware you would need besides the microphones is a soundcard with many inputs (it's very hard to synchronize input between soundcards when you need this much precision). Many soundcards support this, with a stereo mic input and line inputs.   

       Oh yeah, the system also gets better as the square of the number of microphones. So a 4 microphone system is almost twice as good as a 3 microphone system. With enough microphones, you could probably hear a gnat flying around anywhere on your property.
nelso, Dec 31 2003

notexactly, Feb 26 2017

       // We're always interested in unusual noises on or near our 10-acre rural property.//   

       There must be a market for cheap, inconspicuous disposible devices consisting of a button cell, circuitry and speaker that, every few nights at random interval, produce a brief disconcerting noise.
MaxwellBuchanan, Feb 26 2017


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