Creepy Sounds Heard 'Round the World

Last night I was browsing through some Internet radio archives from a religious site and found one about strange sounds heard in the sky around the world.  The first thing the speaker mentions is that there are tons of videos on YouTube documenting this phenomenon.  He, along with various callers on the show, explore many different possible causes of this eerie, trumpet-like noise, including the following:

• Warning of the Apocalypse
• UFOs
• HAARP
• Project Blue Beam
• Pranksters
• Magnetic poles shifting

There are way too many authentic reports for this to be a hoax.