Very low and very loud hum over my head at 3:45 am.Friday morning 1/31/14 at approx. 3:45 am I was awake in my living room and I began to hear a very low and loud hum coming from somewhere, so I stepped outside to try and find out what it was... To give you an idea of how loud it was, I have a service connected disability from the Marine Corps which is "hearing loss" and I did not have my hearing aids in my ears during this time.When I stepped outside I noticed that it was directly over my head! However, it was very cloudy and whatever it was, was just above the low cloud cover. I hurried inside to get my camera expecting it to appear under the clouds at any moment.I stood there for another 4 or 5 minutes listening to it and trying to decide whether or not to call the Sheriff's Department since they took my summer sighting so lightly. I decided to wake my wife and as I was walking toward the door I noticed it getting quieter so I stopped and listened.It slowly got quieter and quieter until it was gone. I suppose whatever it was ascended straight up because the sound stayed directly over my head... I also noticed my two Labrador dogs and my cats were alert and observing the sound also.Later in the morning around 7-8am three U.S. Blackhawk helecopters flew over. I wouldn't think that to be strange if we ever see military helecopters around here, but we don't... We are over a hundred miles from any military base and never see any military aircraft in this area. I am in the country and surrounded only by farm crops and Old Order Amish folks. There is nothing out here.I have no idea what this was, but something with a very low and very loud hum hovered over my property for about 7 or 9 minutes on Friday morning at approximately 3:45 AM.