John-Del wrote:

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There have always been listening devices and there always will be.

I remember reading the clever way the Russians were snooping on the Americans with no bugs within half a mile of the room: they targeted a laser on a window pane of the room they were spying on. The window pane acted like a microphone diaphragm. They then demodulated the return signal which had the room audio modulated on it. Probably not hifi but I'll bet it was usable..


** By all accounts, bouncing a IR laser off a widow is not practical. The beam has to be precisely aligned *square on* to the window and the resulting sound quality is abysmal.

OTOH this simple Soviet invention worked well and had no such issues:

https://en.wikipedia.org/wiki/The_Th...stening_device)



..... Phil