Starting on December 19, 2013, and continuing every night for over a week, I heard a deep-pitched droning sound, punctuated by a loud, but muffled BOOM. Sometimes the BOOM only happened once or twice. Other times, it would sound a number of times, in rapid succession. This went on almost night for over a month. It then became several times a week, and continues to this day. I heard it this morning, at about 4:30AM, and listened to it for an hour. There was no BOOM today...just the deep-pitched droning sound. My husband has even heard it a couple of times.As for the DIRECTION of the sound, it seems to be from above, kind of in an "umbrella" sort of way.Over the last month or so, I have contacted Patrick Air Force Base...NASA...a tech person who works for a local gas company...the 2 local airports...NONE of these folks had an explanation for the sound. However, the NASA person said that I was the 3rd or 4th person to call NASA about a "loud, deep humming sound and some weird explosions". I have reported this already to my LOCAL MUFON investigator...DINAH LECHNER...and we have been working on it together. I would like to have her remain my CASE INVESTIGATOR.THANK YOU for any help you can give with this mystery.