When sound waves travel through the air, they give off tiny vibrations that cause imperceptible movements on the surface of objects that they hit. A study from researchers at the Massachusetts Institute of Technology shows how to take silent video footage of sound vibrations in a glass of water, an empty bag of chips, and the leaves of a plant to make a record of the sounds.

When sound waves travel through the air, they give off tiny vibrations that cause imperceptible movements on the surface of objects that they hit.

A recent study demonstrates how to take silent video footage of sound vibrations in a glass of water, an empty bag of chips, and the leaves of a plant to make a record of the sounds.

They call their method a visual microphone, and it can be used for the passive recording of sound, including conversations or music.

Using footage from a high speed video camera, filtered to show the tiny movements in each frame, the researchers were able to apply advanced algorithms to convert the vibrations back to sound.

They did a series of experiments, including silent video of music being played through ear buds.

After running the video footage through the visual microphone software, they played the recording through audio recognition software which correctly identified the music.