This link, with it's own embedded You Tube videos, is completely mind boggling, scary and causes for me to ask many questions. What in the hell is this? And what is generating noises that whole nations experience, and hundreds and hundreds of people report.
One bit of my guesswork is that this series of events is related to something going on with the ionosphere. I believe that the sun's recent high of level of activity may have indeed loaded up the ionosphere. The sounds could be something to do with the magnetic flux lines surrounding the earth, and that being 'bent' or otherwise stressed during high level solar activity.
Of course this is only my guesswork. Presently I am looking at the history of the sun's activity, as well as that of the ionosphere, during August 2011.
March 2011 to August 2011 has seen hundreds of reports of strange and loud noises coming from the ground or the sky, including tremors sometimes. Some people have reported these sounds before moderate earthquakes in places that normally do not experience earthquakes but only rarely.
Check out this link: http://www.reality-choice.org/159/strange-sounds-all-around-the-world