Elephants can produce noises as low as 20 hertz, a frequency inaudible to humans. (Photo : Wikimedia Commons)
Elephants are known for their loud, trumpeting, but they also communicate through a lower frequency that humans can't hear. Until now, scientists wondered where and how these sounds are produced, and a recent study helps clear up some of the mystery.
To find out how this vocalization occurs, the researchers took a look at the layrnx of the animal, but studying voice production can be a bit trickier with a live elephant than with a human. So when an elderly elephant died in Berlin, the team jumped on it and obtained the larynx.
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What they ended up finding out is that elephants create these low, rumbling noises in a similar fashion that humans do - by blowing air through their vocal cords, only their noises are too low for the human ear.
"The sounds the elephants make are off the piano keyboard," said lead author of the paper Christian Herbst, a voice scientist at the University of Vienna, Austria.The sounds run at a frequency of about 20 hertz, and the human's hearing range is around 50 -7,000 hertz.
The method used was simple: use a tube to blow warm, humidified air through the larynx and see if the vibrations produced matched those made by the elephants. If they did, it would points to a myoelastic-aerodynamic (MEAD) mode of communicating. If it didn't, then it could mean that elephants use active muscular contraction (AMC) instead.
When the warm air was blown through the larynx, the vibrations did match those made by elephants and the team thinks it most likely that elephants vocalize that through MEAD. They have not, however, completely ruled out AMC.
Herbst believes that by looking at how other animals communicate, there is a good chance scientists can get to know more about the origins of voice more clearly.
"It still strikes me as fantastic what we humans, particularly, can do with this system," he said. "We see variations in the laryngeal anatomy and usually, nature has a good reason to come up with slight variations."
Watch a video explaining how the sounds are created: