I can hear the "Hum" most of the time when in bed in my sleeping room. I have been trying to find the location, but so far without success. I know that the sour

I can hear the "Hum" most of the time when in bed in my sleeping room. I have been trying to find the location, but so far without success. I know that the source is not in our house, because I disconnected the house from the electric grid for testing. My best guesses for the source of the "Hum" are: - A transformator station located not too far away from our house. - A nearby neighbor running some machine 24h a day, maybe for heating or cooling. - Sounds of an machine, maybe for waste water treatment, travelling though the sewer pipes. This is my favorite theory. If you hear the "Hum", try to simply accept that it's there and there is nothing you can do about it. This helped me tremendously get back to normal sleeping hours.