How To Use Junkfood To Eavesdrop Through Soundproof Windows

MIT researchers have developed technology that can look at the vibrations of say, a bag of chips, and recreate the sound that made it.

Aug 5 2014, 5:00pm

This article originally appeared on our sister site Motherboard. To see more of their awesome work, head over here.

When you think about cutting-edge eavesdropping tools, your mind probably jumps to tiny microphones, hidden gadgets, and maybe your one friend who's really good at reading lips. But how about potato chip bags? Or plants? Or basically any object in a room?

One of the first things you learn about sound in school is that it's a vibration. So no matter what the sound, you can expect some sort of vibration—on anything sharing the room with the sound's source. Given that, researchers at MIT have developed a technology that can look at the vibration of any given object and recreate the sound that made it. The tech is so amazingly accurate that researchers were able to recreate human speech by scrutinizing the vibration of a measly potato chip bag.

It's not a completely unprecedented idea: In the extremely mediocre season 7 X-Files episode "Hollywood A.D.", Mulder and Scully were able to recreate Jesus' voice from the imprint it had made on some clay. That was the X-Files. This is real.

In his experiments, researcher Abe Davis used an ultra high-speed camera (it records at 5,602 FPS) to record the vibrations of the leaves of a potted plant, a potato chip bag, and the earphones of a set of headphones from behind a soundproof glass window. An algorithm written by Davis and his team was able to translate those visual vibrations into actual sound. Listen to it here:

Crazy, right? The sound recovered from a video of earbuds playing "Under Pressure" was even recognized by Shazam, a temperamental app if ever I've used one.

Now it's possible to "hear" what's happening in another room, or across the room, without having a microphone around at all. Of course, whoever is doing the eavesdropping is going to need to have a straight shot at it, and a tripod to help stabilize the image isn't going to hurt.

But, where exactly are you going to find a clandestine, high-speed camera? Turns out you don't actually even need one. Videos taken with a 60 FPS camera (something your smartphone can do) was less recognizable, but worked nonetheless.

The law enforcement applications for this sort of technology are pretty obvious, though it's not clear exactly when you're going to have the unfettered ability to use a camera, but not a microphone to spy on someone. But, in a press release, Davis said there's some other uses of the tech, as well.

Rather than simply determining what was said, he says we can take a look at the objects that are vibrating to learn something about them. You can learn a lot about an object's structural integrity, he says, by how it reacts when it's bombarded with sound.

That sounds great, but from now on, I'm going to make sure everything I say and do happens in an empty room with opaque walls. It's going to be a sad existence.


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