We’ve all heard of white noise, that static sound the TV makes when poltergeists arrive. There are other colored noise too that mimic natural sounds like rainfall and ocean waves. What they do for us is just now being studied.

Selects: Mangroves: Nature's Best Tree?
44:31

How the Kowloon Walled City Worked
41:27

Short Stuff: In-Flight Entertainment
12:23