Algorithm can reconstruct speech from a pack of chips through soundproof glass

[thewayne]

Very interesting tech. The ability to recover sound by bouncing a laser off of glass has been around for ages, this is different as it just uses a camera and would therefor be difficult to detect. You find a boundary, for example, between a blue and red object. Blue and red combine to make purple, and by watching how it shifts around purple you can reconstruct information.

It isn't easy. An ideal setup would have a camera that could record 2,000 to 6,000 frames per second (FPS), which is damn fast and requires a LOT of light: as the FPS goes up, so does the amount of light for a proper exposure. The real breakthrough by the researchers was to find a quirk in cell phone cameras, which top out at about 60 FPS but this glitch can be exploited to provide the same information.

The defense? Close the drapes.

Their findings will be presented at the Siggraph conference.

http://newsoffice.mit.edu/2014/algorithm-recovers-speech-from-vibrations-0804

Comments

[silveradept]

Interesting. I wonder if the same technique works on objects with the same semisolid properties glass has, such that one could retrieve a palimpsest of sound spoken in the vicinity of the object.

[thewayne.livejournal.com]

If I understand what I read correctly, they need two colors so they can measure the frequency of the varying color shifts between them as the object is hit by the sound, then they can reconstruct the sound. It's not the medium so much as the motion of a light object that is imperceptible to the human eye.

[silveradept]

So it's reading a Doppler shift off of something? That's impressive.