People around the world have been reporting eerie, haunting and almost apocalyptic like sounds.
This phenomenon has surged since 2009 with witnesses saying they hear, grinding metal, trumpets, howling, humming and loud booms or explosions.
But what is it?
This phenomenon has surged since 2009 with witnesses saying they hear, grinding metal, trumpets, howling, humming and loud booms or explosions.
But what is it?