Staying alone in rural Aus (NSW, near blue mountains) and I keep hearing weird vibrating. Hard to explain but it's this very low buzzing noise. Every time that I step outside, however, I can't hear it, but I can hear it clearly from inside. Any idea what this could be?

It's been going on for hours since the sun has set. I have tried recording it but it does not seem to be audible in recordings. I am more annoyed than spooked because it's kind of giving me a headache.

>>40669655 (OP)
Bumping with a recording, not that anything is audible vocaroo 1nvNlljWwWrS