What are strange sounds? What’s causing them? You will maybe find an explanation in the following documentary.
This long video documentary first presents a compilation of the most interesting strange sounds before featuring different theories to what these weird earth sounds are. If you have heard the sounds and would like to skip to the theories start at 09:15
You will find most of these strange sounds on this webpage, all summarized on a strange sounds map.
So what is your preferate explanation?