What is the loudest sound in the world?

There is no one constant loudest sound on Earth. However, the loudest sound ever recorded by human was created by the volcanic island of Krakatoa in Indonesia.

The eruption of Krakatoa took place in 1883 and was so powerful that it split the island in half. It was so loud that it was heard 1,300 miles away in the Andaman Islands, 2,000 miles away in Australia and up to 3,000 miles away in the island of Mauritius. In terms of decibels this sound was over 194, which is when sound stops moving through air and actually starts pushing it. Even at a 100 miles away the sound registered at 172 decibels, which is more than 40 decibels over the human threshold for sound induced pain.