Thanks to humans, the world's oceans today are noisier than ever. According to Dr. Leila Hatch of the National Oceanic and Atmospheric Administration, submarine sounds created by commercial ships, air guns and torpedoes have become a major issue -- particularly for mammals like whales and dolphins.
"Under water, sound travels extremely efficiently," tells us on Soundcheck. "This can prove as a real problem chronically for animals." Hatch joins us to explain how the U.S. government is working to map these noise levels under the ocean to find out where they're the loudest -- and the types of steps that can be taken to bring those levels down.