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http://www.petridishnews.com/news/scientists-solve-the-mystery-of-singing-elephants/ wrote:
Scientists solve the mystery of singing elephants
Researchers at the University of Vienna explain the mystery of elephant infrasounds.
The Petri Dish | Spencer Hardy | Sunday, August 05, 2012

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<<Scientists at the University of Vienna believe that they have solved the mystery of singing elephants. The team of voice researchers and cognitive biologists discovered that elephants sing the same way that humans do. The infrasounds they create are made with the same physical mechanism as human singing.

The use of infrasounds, sounds with pitches below the range of human hearing, is how elephants communicate. Not only can these infrasounds travel several kilometers but they provide elephants with a “private” channel of communication. Scientists say that infrasounds are as low as the lowest notes of a pipe organ.

“Basically they’re singing, but because their vocal folds are so big, they produce these very low sounds,” said Tecumseh Fitch, a biologist at the University of Vienna and an author of the paper, according to The New York Times.

For years, scientists have tried to figure out how elephants make infrasounds. Some scientists believe that elephants purr like a cat by tensing and relaxing the muscles in their voice box. However, scientists note that the sounds produced by this method are not very powerful. Other scientists think that elephants produce infrasounds like human singing. The low frequencies are explained by the elephants’ oversize larynx. Scientists think that elephants produce infrasounds from very long vocal cords slapping together at a low rate.

To discover which methods elephants use to produce infrasounds, researchers took out the larynx of a deceased elephants. Blowing a controlled stream of warm, humid air through the larynx, and placing the vocal cords in the “vocal” position, the researchers manipulated the vocal cords into periodic, low-frequency vibrations similar to infrasounds.

Given that periodic tensing and relaxing of vocal cord muscles is impossible without a connection to the elephant’s brain, low-frequency vibrations similar to infrasounds in the amputated larynx show that the “purring” mechanism fails to explain infrasounds. Therefore, scientists concluded that elephants “sing” like humans. The scientists note that their research shows that the physical principles underlying the human voice are applicable over a wide range of animals. The study was published in the journal Science.>>