[robroys woman]

I remember back in the 70’s when I sold hi-fi there were articles about attempting to produce sound “in thin air” without a physical driver.

I have assumed, since then, that the nut will eventually be cracked. Not that this is it, but it’s a start.

[DiogenesLamp]

I remember back in the 70’s when I sold hi-fi there were articles about attempting to produce sound “in thin air” without a physical driver.

I figured out how to do that in theory several decades ago. Heterodyning two High frequency audio signals (above the range of human hearing) with a differential frequency of what you want the sound to be.

Focus the two sources at a point in space, and you can create compressions and rarefactions that correspond to the audio signal you wish to reproduce.

I've read that people have actually done this, and I pat myself on the back for having thought of how to do it in theory back in the 1980s.

But doing it with light will give you a far greater range, because you have more control with light than you would with high frequency audio signals.