There is apparently a low level hum some hear.... I am one of them. It started for me around 2010 one night...low level rhythmic hum like a generator. I walked everywhere looking for the thing to tell it's owners to switch it off at night.... cause it was annoying ...never found where it came from. Some time ...few years...later I read there are a good few that hear this sound. I suspect maybe 3G comms bouncing off cell towers. It's annoying...louder some places than others and present all the time if I focus. Nowadays I just tune it out.
Maybe you also now are tuned in?
Maybe you also now are tuned in?