What's causing the mysterious sounds coming from the sky that are so loud they set off car alarms?What's causing the mysterious sounds coming from the sky that are so loud they set off car alarms?

Mary Anna (7 March 2012)
"What's causing the mysterious sounds coming from the sky that are so loud they set off car alarms?"

http://www.dailymail.co.uk/sciencetech/article-2110523/Whats-causing-mysterious-sounds-coming-sky-loud-set-car-alarms.html?ITO=1490

Mysterious sounds have been heard booming from the sky all around the world in some cases they were so loud they set off car alarms.
The unsettling noises were heard recently from Europe to Canada, sounding like groans and powerful horns.

In Germany noises coming from the sky were recorded on a video camera and uploaded to YouTube, with car alarms clearly heard going off in the background.