This microphone “sees” the sound … without ever hearing it

He’s a microphone, but he doesn’t listen to: he looks. For example, The Beijing Institute of Technology team has developed a system that captures sounds not thanks to acoustic waves. Nevertheless, but via light. For example, Their “visual microphone” is based on a simple idea: when a sound strikes a light surface. Moreover, like a sheet, a piece of paper, a plastic cup, it causes micro-vibrations invisible to the naked eye. For example, By projecting light on this surface and analyzing the intensity variations of the reflection, researchers can reconstruct the original sound!

A microphone watching instead of listening – This microphone "sees" sound …

So far, this kind of technology required advanced equipment: lasers, very high speed cameras … For example, In short, it was expensive and not very transportable. Major innovation therefore comes from the method used: unique pixel imaging. It is based on a single light this microphone “sees” sound … sensor associated with luminous patterns projected on the object. An algorithm then takes care of reconstructing the vibrations, then the sound.

« Our method simplifies. reduces the cost of using light to capture sounds, while allowing it to be used where a classic microphone would be useless, as through a window “Explains Professor Xu-Ri Yao, team director.

To validate their system, the researchers have placed objects 50 centimeters from a speaker diffusing a musical sequence (in this case, The letter to Élise) and series of figures in English and Chinese. Result: the sheet of paper made this microphone “sees” sound … it possible to reconstruct an intelligible sound, especially in the low frequencies. The treble, they were a little more distorted, but partially corrected thanks to a signal processing filter.

One of the advantages of this technology is its computer lightness: the generated data flow remains low (4 MB/s). which authorizes continuous, locally or cloud records. Ultimately, the system could be miniaturized and integrated into everyday devices: phones, drones, even security cameras.

And this is where use cases are multiplying. One can imagine its use in the rescue (listen to the voices under the rubble). in the industry (diagnose a machine from a distance) or even in medicine (measure the heartless heart rate). But the question of privacy is never far away: this device can also capture a conversation without microphone. wire, nor physical presence. Just see, to hear.

Researchers assure not wanting to create a espionage tool, but a measurement this microphone “sees” sound … tool in hostile environments. They are now working on improving sensitivity and lengthening the scope, for use in real conditions.

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