Dr. Poppy Crum

They're not changing, they're changing data

subtly what frequencies they elicit the call at so that it always comes back in the same frequency range because that's where their heightened sensitivity is.

So otherwise, you know, so they're modifying their vocal cords to make sure that the call comes back in the same range.

And then they're tracking how much they've had to modify the call.

Absolutely.

But also so they're shaping the sounds they send out so that whatever comes back is in their optimal neural range so that they don't have to go through more neural plasticity that they already have, like circuits that are really dedicated to these certain frequency ranges.

And so they send it out, and then they're keeping track of the deltas.

They're keeping track of how much they've had to change it.

And that's what tells them the speed.

So that constant frequency is a lot like, you know, the ambulance sound going by.

That's the compression of sound waves that you hear as a...

when things move past you at speed.

That's the Doppler effect.

And then there also, it has usually a really fast FM frequency modulated sweep.

And that lets me take kind of an imprint of, you know, so one's telling me the speed of the object.

Another one's telling me sort of what the surface structure looks like, right?

That FM sweep lets me get, you know, a sonic imprint of what's there so I can tell topography.

I can tell if there's a, you know, a moth on a hard surface, right?

Yeah.

So what's beautiful about other species is you've got a little moth and you've got nature's predatory marvel.