Yes! Been noticing this for a while now. I do basic EVP sessions in a couple of old sites around Dorset and almost every time something decent comes through, there's this burst of static right before it, like the audio just gets agitated or something. My mate thinks its just equipment interference but I don't buy that, it happens too consistently.
What I find interesting is whether the static is actually part of the process - like whatever is trying to communicate needs to build up some kind of energy first and the static is the bleed-off from that. Probably talking nonsense but it feels right.
Has anyone tried logging exactly how long the gap is between the static burst and the actual EVP? I've been meaning to do that properly but haven't got round to it yet. Would be curious if theres a pattern there across different people's recordings.