You can do something similar with a laser. The laser is reflected off of an object and into an receiver where it is converted into audio. The two techniques dif

You can do something similar with a laser. The laser is reflected off of an object and into an receiver where it is converted into audio. The two techniques differ in methods, but they both rely on measuring the movement of secondary materials affected by sound waves which can then be used to infer speech. * https://hackaday.com/2010/09/25/laser-mic-makes-eavesdropping-remarkably-simple/ https://hackaday.com/2010/09/25/laser-mic-makes-eavesdroppin...