Microphone-Less Camera Can Record Sound By Seeing Its Vibrations

Microphone bleed-throughs can be such a pain when trying to record anything. New technology from Carnegie Mellon University (CMU) has developed a way for cameras to wean off relying on microphones and instead see sound to record it. Vibrations could be picked up and recorded before being transformed back into sound waves.  

In a paper titled Dual-Shutter Optical Vibration Sensing, CMU describes a new way of developing optical microphones using cheap camera gear, where before state-of-the-art equipment had to be used in order to record without a microphone.  

When recording music, musicians are often placed in separate rooms or record in intervals as microphones cannot handle all the instruments playing at once. The result is often a cacophony of sounds that have no quality to them as microphones cannot distinguish between the waves moving through the air. So, each instrument is individually recorded, and a sound engineer will mix everything together. This is also why recording studios have so much equipment filling the rooms and mixing boards are so huge.

Now, researchers have found a way to capture quality music using cheap camera equipment to get rid of the bleed-through. A laser is attached to the lens of a camera and shot directly at an instrument, for example, if someone was plucking strings on a violin, it would be aimed at the movement of the strings being plucked. The vibration of the violin will also be picked up and analyzed, translating its minute movements back into sound.  

Previous optical microphones were especially pricey as they needed to capture vibrations moving up to 20,000 a second. The cameras used in the study worked at 63 frames per second, which is significantly less. The genius behind it was that, instead of one expensive camera, the workload will be split over two regular cameras—one with a global shutter and one with a rolling-image shutter. The data collected is sent through an algorithm that analyzes the vibrations against each other, which results in being able to read vibrations up to 63,000 times a second, providing a much more accurate reading.  

While this could open the door for musicians and bands playing in live settings while being recorded at studio-quality levels, the sound is still not as clear or high-fidelity as a regular microphone. Though, it is a promising beginning and one that certainly will have a future in filmography and music someday.  

[via Gizmodo and DIY Photography, cover image via Photo 2665238 © Chrisharvey | Dreamstime.com]