Yeah this has been a recurring thing for me over the past year or so. I use a Zoom H5 and before I even hit record sometimes I get these sharp interference bursts, usually 3-5 seconds, then it clears up completely. At first I chalked it up to RF interference from my mobile but I started leaving my phone in the car during sessions and it still happens.
What I find interesting is that the sessions where I get those pre-session bursts tend to produce better EVP results. Not always, but often enough that I've started logging it. Could be coincidence and I'm just pattern-matching, I genuinely don't know. But its happened too consistently to ignore.
Anyone else actually tracking this systematically rather than just noting it anecdotally? I want to know if theres a correlation with location type, temperature, anything measurable. Gut feelings are fine but I'd rather build some actual data on this if people are willing to share specifics.