Yea i've heard these popping noises too, i know it's outer worldy was just trying to keep that basis out, we aren't there yet.
For my type of PATM I'm convinced it's not electrical but rather some sort of weird atmospheric pressure changes i.e. knocking noises in the refrigerator (every place I've lived, new refrigerators in some places) and other ambient things I've observed that has to due with certain popping noises. The same type of popping noises that would occur with a partially empty plastic bottle of water as you change altitude, but all right here wherever I am. It's outer-worldly in my opinion.