Although I think that this video probably explains the 'truth' of what is going viral, I do have to say, that I have personally experienced this phenomenon, but on a much lower scale. About 6 months ago, I was going into work and as I walked from my car to the front entrance, I could clearly hear a low rumbling humming sound. It wasn't specific enough to pin point a location, in fact, it seemed to be coming from everywhere, which is why it got my attention in the first pace. That, and the vibrational sound was non-specific as well...not like a running engine or machine makes, although it was similar. I just assumed it must be some type of machine operating that I hadn't ever heard before. The next day, I heard it again. Because it was so different, I waited outside, listening to try and discern what it was. Again, it seemed to be coming from everywhere with no point of origin. I went to get some colleagues to come out and listen as well. None of us could determine what it was or where it was. Over the next few days, this sounds would just show up, last about 15 to 20 minutes and then mysteriously stop. After about 6 times, it never returned. I have never heard that type of sound again. I tried doing some research, but at the time, I these videos had not surfaced. I did find where there are people hearing a humming noise that is disturbing to them, but others do not hear it. It is not the ringing in the ears type of sound. It is a low grade humming. What I experienced was by no means as dramatic as these videos, and, it was audible to others but, it was an unfamiliar sound that seemingly had no point of reference. I haven't a clue what it was.