I am not sure it is really as basic and obvious as you imply. The comparison between the "reversibility" of laser speakers/microphones and the reversibility of

I am not sure it is really as basic and obvious as you imply. The comparison between the "reversibility" of laser speakers/microphones and the reversibility of normal speakers/microphones is a bit off, in my opinion. For starters, laser microphones do not use the photoacoustic effect[1] that the device described relies upon. Whereas the reversibility of normal speakers/microphones is because both devices use the same physical process. That it's possible to build a microphone using lasers and to build a long-range sound generating device using a laser doesn't imply it's obvious (or even possible) to do so for any given audio production or recording technique. E.g., if I can generate audio using a flickering lightbulb, it is not clear that a flickering lightbulb can be used as a microphone. [1]: https://en.wikipedia.org/wiki/Photoacoustic_effect https://en.wikipedia.org/wiki/Photoacoustic_effect