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This device is a handheld sound scanner, which identifys where each nearby sound comes from, and then shines a visible laser beam on it to identify the origin of the sounds. It would be a useful tool for when you hear something, but can't figure out where the heck the sound is coming from.
It would
be lightweight, and have at least 4 (but prefereably 8) microphones, arranged in a trapezoid or cube or whatever, with each mic at least 2 inches from every other mic.
It would have a small computer, which would not just listen for sounds, but would identify how much of a delay there is for each sound to reach each mic, in comparison with when it reached the first mic (the one nearest the sound source).
With a bit of math, it would identify the direction and distance from itself to the sound source, based on the timing differences.
Then, using a laser and a small high speed motorized mirror, it would illuminate the sound source.
For an enhanced way to identifying sounds, it would use the laser&mirror to "draw" a circle, and play (through a pair of headphones or earbuds) those sounds which originate within the illuminated circle.
ShotSpotter GLS
http://www.paloalto..._story.php?id=10000
[bigsleep, Mar 19 2009]
[link]
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Obviously well baked for the military and police forces in jumbo form, but would be great in a pocket edition. For my use in an apartment, I'm not so sure a multitude of wall reflections wouldn't confuse it. |
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Sound reflections mainly occur off of smooth surfaces. The reflected sounds would *seem* to be coming from your walls, floor, and ceiling. You, being a human with some common sense, can ignore any sound origins which don't make logical sense. |
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So if your cell phone rings, and it shines the light on the ceiling and under your bed, you can ignore the ceiling :) |
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(If you meant that the reflections would interfere with the calculations of where sounds are coming from, don't worry-- that kind of confustion can only occur if the reflected sound is closer to the original sound than distance between microphones. And even then, it should still be able to distinguish between "first occurance of sound X" and "second occurance of sound X") |
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What about a different room/floor. There maybe no direct paths for the sound and what the sensors hear is only reflected sound (largest amplitude). Maybe back correlation could fish out a heavily attenuated direct signal ? |
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How does the laser pointer cope with diffraction? |
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bigsleep, the device doesn't distinguish between "original" sound and reflected sound. |
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If it hears original sound, it would shine the laser on the sound source. |
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If it hears reflected sounds, it would shine the laser on each of the surfaces that the original sound was reflected off of (i.e., each "apparent" source of sound). |
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It would be up to the human user to distinguish between what the laser light means. |
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If you're in a room, and some sound is coming into the room from down the hall, it's doubtless entering by bouncing off the doorway, and the laser will light up the region of the doorway that seems to it to be the source of the sound. |
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You, the human, would need to use common sense to figure out what that the point of light on the doorway means. |
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