   By , LiveScience Senior Writer    • close     African
elephants in Amboseli National Park in Kenya.     View Caption
It turns out that they do it in the same way that humans talk,
pushing air through their vocal cords to make them vibrate.
Elephants can go much lower than humans, however, because their
vocal cords are eight times longer.  "The sounds the elephants
make are off the piano keyboard," said study researcher
Christian Herbst, a voice scientist at the University of Vienna,
Austria. In fact, at less than 20 hertz in frequency, the main
components of these ultra-deep calls aren't detectable to the
human ear.   Recommended: Are you scientifically literate? Take
our quiz  Until now, researchers weren't sure how elephants
produced such low sounds. In fact, it's difficult to study voice
production in animals in general, Herbst told LiveScience. In
humans, researchers can insert cameras through the throat into
the larynx, or voicebox, while people make different sounds.
Animals tend to be less coopera