Extract info from Audio

Researchers are able to recover sound through soundproof glass by recording the vibrations of a plastic bag.

Researchers at MIT, Microsoft, and Adobe have developed an algorithm that can reconstruct an audio signal by analyzing minute vibrations of objects depicted in video. In one set of experiments, they were able to recover intelligible speech from the vibrations of a potato-chip bag photographed from 15 feet away through soundproof glass.
In other experiments, they extracted useful audio signals from videos of aluminum foil, the surface of a glass of water, and even the leaves of a potted plant.

This isn't a new idea. I remember military security policies requiring people to close the window blinds to prevent someone from shining a laser on the window and recovering the sound from the vibrations. But both the camera and processing technologies are getting better.
News story.