Researchers at the Massachusetts Institute of Technology (MIT) have found a way to use a potato chip bag as a tool for listening in on people's conversations.
The technique involves studying small vibrations that are triggered when sound strikes the surface of an object, which allows the research team to obtain audio, according to Discovery News.
Using a high-speed camera placed behind a soundproof window, the team managed to recreate spoken words and music. The device is capable of "listening" to sounds created in the room by applying a complex algorithm to the visual information it finds.
A potato chip bag was used by the team to recreate speech, and was even able to reconstruct conversations when it was filmed from 15 feet away through the soundproof glass, GMA News reported. The method can also be used to obtain sounds from aluminum foil, a potted plant, and a glass of water.
"This is new and refreshing. It's the kind of stuff that no other group would do right now," said Alexei Efros, an associate professor of electric engineering and computer science at the University of California at Berkeley. Efros added that the technique was similar to something "totally out of some Hollywood thriller."
"You know that the killer has admitted his guilt because there's surveillance footage of his potato chip bag vibrating," he said.
The camera is only capable of reconstructing audio from video if the frame rate of the video sample is higher than the audio signal's frequency, Discovery News reported. To make sure of that, the team used high-speed cameras that could capture between 2,000 and 6,000 frames per second.
The technique also helped the researchers obtain a limited amount of audio from standard smartphone cameras, which provide more limited information than the high-speed cameras, such as number of people speaking in the room, as well the gender of the speakers.
While the "visual microphone" technique has potential uses for forensics and law enforcement, the team is looking to use it for creating a new type of imaging to determine the structural properties of objects, Discovery News reported.
Abe Davis, an MIT graduate student in electrical engineering and computer science and first author of the new paper on the technique, said the sound can provide information about the object "because different objects are going to respond to sound in different ways."
"I'm sure there will be applications that nobody will expect. I think the hallmark of good science is when you do something just because it's cool and then somebody turns around and uses it for something you never imagined. It's really nice to have this type of creative stuff," Efros said.
