Steady Humming SoundUnexplained Noises From Sky On the evening of September 13, 2015, I was in the process of settling myself down for sleep, when I became aware of a humming sound. It seemed to sound like it was coming from outside.I wouldn't say the sound was "noisy", but more like a steady hum.Mid-tones. Steady.I got up and went outside to investigate. The neighborhood was quiet, no dogs barking, no cars passing by.The sound was all encompassing, yet I got the sense the sound seemed to have originated from the sky above. Northwest direction.I tried to capture the sound on my tape recorder, but I was unsuccessful.I was not frightened in any way, but curious more than anything.I went back to bed, say, 40 minutes later, with the hum still continuing, before I drifted off to sleep.I wish I had more details to give you.