Elephants Play Infrasound Marco Polo

By Laura Fitzgibbons

Elephants have an entire inner world and community that was recently completely out of reach of human observation. It turns out that we are unable to hear a large amount of the sounds that they make. Whenever the low vibrations they make fall between 1 and 20 hertz, they are within the parameters of infrasound. An elephant's infrasound call can be heart by another elephant as far away as more than 6 miles. The noises serve many purposes, but they are most commonly used by the female leader of a group of elephants. She may use her sounds to explain to the group how to move to the next location, or she may call out her location to her calfs while they respond with their own locations in alternating order. Instead of Marco Polo, perhaps they are saying "Baby elephant, Mama elephant." Adult male elephants also rely on infrasound calls, although the purpose is more often to deter their mating competitors. 

Possible Acoustic Models

The part of an elephant's vocal chords used for infrasound is a bit different from the muscles they use for their regular chatter. Their larynx may emit sound through myoelastic-aerodynamic vibrations (MEAD), or active muscular contraction (AMC), when the brain directs vocal chords to contract and expand in a rythmic pattern, similar to a cat purring. 

Cornell University's Elephant Listening Project

Bioacoustics researcher from Cornell University's Elephant Listening Project, Katy Payne, was given the opportunity to spend one week by the elephant enclosure at a local zoo, where she observed that the elephants participated in “large, highly-coordinated social groups.” After a while she started to notice a “throbbing in the air, kind of a pulsation in her ears, sort of the feeling you get when the windows are rolled down wrong in your car.” Eventually she wondered if the sound was lower than the frequency humans could hear and whether it might actually be produced by the elephants. Sounds observed in the infrasound listening project were collected and compared with a large database of similar elephant sounds collected over many years.

According to Katy Payne, “very low frequency sound travels much better than higher sounds.” so the elephants have a “long distance communication system.” This is one way to explain how researchers have noticed over time the elephants are able to sense what other members of their group are doing even at a great distance.