Mates, I mostly lurk here because I'm a UFO lad first and foremost, but this thread dragged me in because I've noticed the exact same thing on nights when I've had my Zoom H5 out on the moor and caught something weird.
Not EVP exactly, but right before I've picked up unexplained sounds, there's this brief static crackle - almost like the recorder is clearing its throat before delivering bad news.
My working theory (and feel free laugh, I'm used to it) is that whatever's causing the phenomenon is drawing on local electromagnetic energy first, and the static is basically the recorder throwing a little tantrum about it. Could also just be interference from my own equipment, obviously - I'm not ruling out the boring explanation.
What recorder are you using? Because I wonder if this is partly a hardware sensitivity thing. Some units pick up EM fluctuations that cheaper recorders just ignore entirely.
Also genuinely curious - does the static come through clean audio or does it corrupt the surrounding file? Because if it's only a burst and then the audio recovers cleanly, that's harder to explain as simple interference.
Anyone tried running a basic EMF meter alongside the recorder to see if there's a correlation? Seems like the obvious next step before drawing any conclusions. Dartmoor's got enough genuine weirdness without us chasing red herrings.
