The HUM

Electrical devices on the grid, or perhaps it's just "the grid" itself emit this barely audible hum. If you've lived your life connected to the grid you probably don't notice it but once you get away from it then it's very audible and sleep disturbing each and every time you have to suffer it. I don't notice it when I run into a convenience store for a bottle of water, but I dang sure notice it in a hotel room in a strange city.