If you want to hear an elephant sing, your best bet is to watch Disney’s Dumbo. The behemoths communicate with low-frequency rumbles, called infrasounds, that can travel more than a mile. Scientists wondered whether elephants create them by purring like cats or by singing like humans. Cats tense and relax their larynx muscles for each pulse of sound, while singing humans’ vocal cords vibrate as air passes over them. To solve the puzzle, researchers whooshed warm air through an elephant's layrnx, simulating breath. When the vocal cords were placed in the right position they produced low-frequency vibrations just like infrasounds. Angela Stoeger, an elephant communication specialist at the University of Vienna and lead researcher, says, “Elephants vocalize using the same physical principles as we do, but their immense larynx produces very low notes” that the human ear can’t detect.