Scientists have long wondered how the elephant makes its guttural, low-pitched call. Now researchers at the University of Vienna believe they have the answer: the pachyderms' vocal folds vibrate when air blows past them - just as happens in human throats. The folds behave something like a flag in the wind.
Biologist Angela Stoeger has studied elephant vocalization for years.
"The most common vocalization is the low frequency rumble, with the fundamental frequencies in the infra-sonic range, below the range of human hearing," she says.
To find out how the animal does it, Stoeger took part in a unique experiment, devised by voice scientist Christian Herbst, now of the University of Olomouc in the Czech Republic. Their team took the donated larynx of a dead elephant, donated by a zoo, and attached it to Herbst's custom-made larynx apparatus.
"We got the larynx, we cleaned it up, we mounted it on a vertical tube and then we blew humidified, heated, air through the trachea," says Stoeger. "We had to adduct the vocal folds so that we changed from a breathing position to a phonatory position and then the vocal folds started to vibrate and we could document everything with sound, with high speed video recordings and other methods."
Their footage clearly shows how the elephant's vocal folds behave.
His team disproved the theory that an elephant's low-level rumbling is caused by regular contraction and relaxation of laryngeal muscles, Herbst says.
"You can imagine that this works like a flag in the wind, for instance," he explains. The air flow causes the tissue to vibrate. Locally-created pressure changes between the vocal folds are propagated through the elephant's mouth, and possibly also through the trunk, creating what listeners perceive as sound.
Broadly speaking, voice works the same way in humans, says Herbst, despite the obvious anatomical differences. He believes that further research using the elephant as a model could lead to new methods of voice coaching in humans, making the most of the similarities between man and beast.
Meanwhile, what's the elephant saying? That remains to be seen, though there is increasing evidence that animals have far more complex communication than had once been thought. Any cat or dog owner knows that the beloved pet has as many as dozens of clearly different vocalizations. Perhaps without thinking about it, the owner starts to realize that a particular bark or meow means "I want to go out," or, "Supper. Now. I. Am. Not. Kidding."