Singing Rats (audio) University of Illinois at Urbana-Champaign Loading audio... Caption Rats like those used in University of Illinois speech and hearing sciences professor Aaron Johnson's study make ultrasonic vocalizations (USVs) that are above the range of human hearing, but special recording equipment and a computer that lowers the frequency of the rat calls allows humans to perceive them. As the recording shows, the USVs sound a bit like bird calls. Credit Aaron Johnson Usage Restrictions This audio file may only be used in concordance with the information presented in this release. 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.