Forever echo: Can a sound wave go on forever?

Today we shout out our love for the ECHO! (echo echo) Discover how these curious callbacks happen and why we hear them in some places but not others. We'll also play you the longest echo in the world and take you to an echo-proof room. Plus, an actual echo stops by to share its new podcast and we hear the answer to this Moment Of Um question: why can wild animals drink dirty water when humans need clean water? Today’s episode is sponsored by Loacker (loackerlove.com/powermom2019), Goodnight Stories for Rebel Girls the Podcast (rebelgirls.co/podcast), Philo (philo.tv/brains) and New Cloud Control Cat Litter by Arm & Hammer. You can support the show at brainson.org/donate