Yeah this happens to me constantly and I've been trying to figure out if it's just interference or something more intentional. I do a lot of sessions out at old Norfolk churches and farm buildings, and the static burst almost always comes about 2-3 seconds before a clear EVP comes through. Too consistent to be random in my experience.
I've started marking the timestamps whenever I hear it during playback so I can see the pattern across different sessions. Out of maybe 40 recordings over the past year, I'd say it happens before a strong EVP roughly 70% of the time. The weaker or class C stuff doesn't seem to have the same buildup.
My theory is that whatever is manipulating the recorder needs to build up enough energy to actually produce the voice, and the static is kind of the overflow from that process. No idea if thats actually whats happening but it fits what I'm seeing in the data.
Anyone else tracking this systematically or is everyone just going off gut feeling? Would be really useful to compare notes properly.