In this post you get a compilation of these weird noises from the sky that we were used to listen in 2012 just before the Maya calender ended! Are they back now?
Strange Sounds from the sky in Curitiba Brazil - July 9 2013

The recorder of the video had always a foot back from videos of strange sounds coming from the sky as they seemed to be haoxes. This until he witnesses the phenomenon on July 9 2013. The metallic echoeing and rumbling noise started around 3 am and lasted intermittently for approximately one hour. At the beginning, it sound very similar to a bell. He has never listened to something like this since he is around (lots of years). Sometimes, the sound was very loud and scary, without any specific direction, but coming from above, from the sky. The sky is very frightning, is terrible!

Strange Sounds in Mississauga Canada: There is The Hum: The Mississauga's Hum! - July 09 2013

These strange sounds from the sky were recorded in Mississauga, Canada at around 5:09 am on July 09 2013. This just after the floods of "biblical" proportion, which hit the Toronto region, breaking records @ 126 mm in under 2 hrs! In normal times only 74 mm of water fall during the ENTIRE month of July. A coincidence, a warning, an earth cry? Do not listen to the car passing by but to the low rumbling and frequency noise in the back. There is The Hum: The Mississauga's Hum!

Strange Sounds in the Sky in Clearwater Florida - July 8 2013

The recorder lives in the Clearwater Florida area. He describes the sound as a low rumbling that stops suddenly and gets so loud sometimes that he can almost feel it. During the footage, there were no winds and no rain storms around. Good catch and thank you for sharing it.