Have you got any examples that you could play for us?

Yeah, yeah, absolutely.

I, I do.

Firstly, let me say there's a whole, as you say, there's a whole raft of tools, th- the cheapest of which cost about £2 or £3, um, and they're the repurposed, uh, anyo- anyo- anyone listening who's a little bit older may remember the old analog telephone headset bugs that you'd stick on the back of a headset of a telephone to record a conversation, and it, they work through Faraday's law.

It's, it's a closed coil of wire.

So basically it's got lots and lots of turns of wire attached to an input plug on a recorder.

And a ma- you know, if you, if you bring a closed coil of wire into a magnetic or electromagnetic field, an electrical current will be generated in the closed coil.

Are you, uh, do you often use hydrophones yourself? Have you got any sounds you can play for us?