Cut to the Chase (IMAGE) Brown University Caption Bats use harmonic variation to distinguish the echoes of obstacles or other background noise from the chosen target. It happens instantaneously. Credit Simmons Lab, Brown University Usage Restrictions None 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.