I was sound asleep,about 2 - 2:30 in the morning and was awakened by this sound."subsonic" seems to describe it. It was not like the backfire of a car, or a sharp sound like the breaking of the sound barrier, both of which I would recognize. and at the same time my body felt it had just been dropped back into my bed,(but I was completely under the covers)or I was just feeling the vibration of the "boom" .The sound was just above my house. My bedroom is on the second floor. The impression I got was that something was just lifting off above the house right above my bedroom and then it was gone. I realized that something out of the ordinary had occurred but I did not get up and look out the window. I turned over and went back to sleep. This type of event has never occurred before. I am not claiming an abduction. I did not report this before, until I read another reporting by an woman whose felt a "virbration" inside her house and an electrical interference with her television and stepped outside and had a sighting, so thought I should probably share this experience.