Interesting thread. I haven't personally had a missing time experience but I've spoken to maybe a dozen or so witnesses over the years doing cryptid research out in the Norfolk broads, and the humming detail keeps coming up unprompted. That's the bit that always catches my attention - they never seem to mention it until you ask the right questions, like they'd almost filed it away as unimportant.
What I want to know is whether the humming felt external, like something in the environment, or more like it was inside your head. Because the accounts I've collected are split pretty evenly on that and I'm not sure what to make of it. Could be two different phenomena entirely, could be the same thing experienced differently depending on the person.
Anyone here actually gone back to the location afterwards to see if theres any geological or infrasound explanation? That would be the first thing I'd want to rule out before going further with it.