I figure bats' brains must formulate some kind of image from their sonar so why not a computer chip in a pair of sound based night vision goggles. Great for storming the hostage takers because they see through the smoke grenades in the dark. Also good in the film processing lab. Can your enemies with nightvision see your goggles' IR emitter's beams? Certainly not if you use the sonar variety. (Unless they are too). Definitely not good for long range, and might set off motion detectors.-- davidcreede, Oct 23 2003 Sonar 3DTV http://www.halfbake...m/idea/Sonar_203DTVwe all ready baked this one! [mr2560, Oct 04 2004] Ben Underwood - Blind, but could see with sound http://www.benunderwood.com/index.html [MisterQED, May 10 2010] Did you just rent "Daredevil" or something?-- Overpanic, Oct 23 2003 How well do ultrasonic waves travel through air, anyway? It definitely has to be ultrasonic, because normal hearing-range sounds have wavelengths so long that you'd never be able to distinguish any detail.-- krelnik, Oct 23 2003 This works... 1mm resolution at about 300 Khz... with good amplification you can use natural background noise... but every time you move you get serious bizarre image distortion due to extreme doppler effects. See link for more info.-- mr2560, Oct 27 2003 huh, this is pretty good...so where's the pastry ? [+]
[edit: ah, 2004]-- FlyingToaster, May 10 2010 If you are interested in this subject, there was a great show on a Ben Underwood (link) who was (sadly I just this moment found out he passed) the best at echolocation.-- MisterQED, May 10 2010 random, halfbakery