Christian Herbst and Angela Stoeger from the University of Vienna in Austria are the first to reveal how elephants make guttural infrasonic calls based on physical analysis in the Oct. 16, 2013, edition of The Journal of Experimental Biology.
The examination was made possible by the demise of an African elephant at the Berlin Tierpark zoo. The researchers collected the elephant’s larynx and were able to make elephant sounds by blowing air through the voice box. Guttural infrasonic calls have frequencies below 20 hertz.
Elephant vocal cords are orientated at an acute angle in relation to the air stream based on CT scan analysis. About 40 percent of the elephant vocal cords are sheltered from air flow. Elephant vocal cords are 180 percent thicker than human vocal cords.
Elephant vocalizations occur when the vocal cords are separated most of the time. Humans produce most of their sounds when the vocal cords contact each other.
The wave pattern of elephant vocalizations involves a single wave form. Humans produce a wave form in each vocal cord. The two waves become superimposed on each other to produce coherent sound in humans.
This research is the first to examine elephant sounds on the basis of physical evidence and should settle a long standing debate among biologists about how elephants make sounds. It is difficult to examine the vocal cords of a live elephant even with sophisticated medical equipment due to size constraints and uncooperative elephants.