Hi,

This is real! We started our startup based on this principle. Do note that these emissions do not occur often, think about up to 10-100 per hours in stress states. For a small background read, read this (not our research): https://www.cell.com/cell/fulltext/S0092-8674(23)00262-3

If you are interested I recommend using a MEMS microphone, sampling at 384 or 500 kHz and triggering at frequencies between 20-200 kHz.

There is several people who have made these solutions for detecting bats using pico's: https://www.geeky-gadgets.com/raspberry-pi-bat-detector-17-0...

If you want something off the shelf look into something like this: https://batsound.com/