I'm sorry I didn't see this earlier.

I say you could pick up EVP's on any audio. We personally use an olympus recorder we picked up from Best Buy. I'm not sure the exact model number but in my opinion make sure you get one that has the letters PC in them(at least that is with the Olympus). These are the ones that you can download on to your computer and transfer to cd incase you get anything good.
As far as how to catch them. Obviously there is no set way.

We have gotten some audio where we're just having a normal conversation and something interjects. We've gotten a few where it seems to be reacting to what we have said. We've left one in a room before and gotten some things. So there is no one thing you have to do to catch one. Hope this helps.

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