Like many other life-forms including whales, pigeons, and hippos, . Scientists have been studying this low-frequency communication to better understand elephants' breeding habits, as well as the pachyderms' ability to coordinate movement while traveling in separate groups. By conducting an infrasound field study in Africa using a custom-made Pachyderm 2 loudspeaker emitting sounds below 60 Hz and recording them at varying distances up to 125 yards away, elephant expert William Langbauer determined that infrasound waves can travel unimpeded by leaves, trees, and even air—all of which easily absorb higher-frequency sound waves. In doing so, he proved that infrasound is an ideal way to communicate over long distances. In fact, Langbauer estimates elephants can hear infrasonic calls more than 2-1/2 miles away.
On a similar note, the U.S. Geological Survey's Jonathan Hagstrum believes that birds use infrasound in the same way humans use GPS: by listening to low-frequency sound waves that the earth produces and following their origins as a map toward home.