[tim333]

There's a link to one of the IEEE articles here https://spectrum.ieee.org/semiconductors/devices/how-we-reve...

with a recording of sounds recorded at the embassy and their attempts to reproduce it. To me the microwave theory seems a better fit.

[scottlocklin]

This is the one I had in mind:

https://spectrum.ieee.org/semiconductors/devices/finally-a-l...