Elephants rumble to communicate, sending vibrations across the landscape that other elephants can feel through their feet. But until recently, no one knew how they made their distinctive thundering sounds. Were they purring like cats, or were their voices just very low?  A new study in the journal Science suggests an answer: Elephants rumble the same way people talk or sing, by blowing air past their long vocal folds and letting them vibrate back and forth. These folds are the largest to have been demonstrated to make sound in this way.  “Basically they’re singing, but because their vocal folds are so big, they produce these very low sounds,” said an author of the paper, Tecumseh Fitch, a biologist at the University of Vienna.  Previously, some scientists favored the analogy to cats: To purr, they twitch their vocal folds rhythmically, because the folds are otherwise too short to make such low noises. But Dr. Fitch and colleagues suspected that elephants’ four-inch-long vocal folds could make deep sounds while vibrating freely.  The core pitches of many elephant rumbles are too low for human ears; we hear only the higher overtones and feel the lower vibrations in our chests if we’re standing close enough.  Dr. Fitch and colleagues made their discovery after recovering a larynx from an African elephant that had died at a Berlin zoo. They attached the larynx to a pipe and blew warm, humid air through it while recording the sounds and capturing its movements with high-speed video. From the first time they tried it, Dr. Fitch said, the larynx made the unmistakable sound of an elephant.  “Cows mooing, elephant rumbles, bat echolocation: They’re all made by the same process,” he added. “That we have a physiological theory that can explain that range is really remarkable.”
The thundering rumbles that elephants use to communicate are produced by a mechanism more akin to the way people talk or sing than to the way cats purr, say scientists who analyzed an elephant larynx.