By Susan Milius
Elephants don’t purr so much as sing when they unleash low-frequency rumblings at friends and foes kilometers away.
Too low for humans to hear, the infrasonic components of elephants’ calls have at times been attributed to a process similar to a cat’s contented thrum. But new measurements made by blowing air through the voice box, or larynx, of a deceased zoo elephant suggest that the mechanism is actually a (much bigger) analog to a person speaking or singing.
Cascades of fast, active muscle contraction give cats their purr. Biologists have speculated that some similar muscle twitching creates the deep throbbing of elephant infrasound. But elephants can get their rumbles going just by exhaling air through their vocal tracts, says Christian Herbst of the University of Vienna. With the new demonstration of air power, Herbst says, “there’s no need to go into the purring hypothesis.” He and his colleagues make their case for superlow elephant song in the Aug. 3 Science.