When Does a Sound Stop Being Noise? (VIDEO) Smithsonian Tropical Research Institute This video is under embargo. Please login to access this video. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Caption Recordings of the sound of rain convinced two species of bats to stay in their roosts, but eventually, they realized that it was not raining left their roosts to forage. Credit Smithsonian Tropical Research Institute Usage Restrictions Credit: STRI License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.