By looking at the minute vibrations in high speed video, researchers at the Department of Engineering of the Catholic University of America have created a method for extracting sound data from high-speed silent video footage.
From the release:
While this wouldn’t work for, say, extracting sound from old silent film, the researchers say they could extract conversations from vibrations at a “far distance,” a prospect that is at once fascinating and a bit scary.
The paper, “Audio extraction from silent high-speed video using an optical technique,” appeared in the journal Optical Engineering.
This technique is not new – MIT researchers were able to read sound from a stray potato chip bag – but this method uses a simpler image matching system to sense audio.