Around 1:30 this morning, I heard The Hum.
It lasted for about an hour. I was laying in bed trying to fall asleep when I noticed an unusual sensation. I rolled over, sat up, walked around the room, looked out the window, nothing changed its power. I didn't feel like I was "hearing" it, per se, but it was definitely not blood in my ear vessels nor tinnitus, both of which I have experienced many times. It was extremely low frequency, sort of like that initial sound you hear when a helicopter is approaching and you are indoors. Its omnipresence made it feel like it was literally inside my head, I imagine a few more hours of that and I might have gone insane. Other rooms in the apartment offered no relief or change, the only thing which did change it was stepping onto the balcony, which I did to see if there was some large boat moving up the Clyde, or some other discernible industrial origin of the Hum. There was not, although it did seem louder outside, but less intense, if that makes any sense at all.