For toothed whales, sound production is all in the nose

Dolphins, porpoises, killer whales, sperm whales and other toothed whales produce an array of sounds - to find prey employing a sonar-like system called echolocation and to communicate with other members of their species. "Echolocating toothed whales make the loudest sounds in the animal kingdom by forcing highly pressurized air past structures called phonic lips in their nose," said Peter Madsen, a sensory physiology professor and expert in whale biology at Aarhus University in Denmark, co-leader of the study published in the journal Science. But the critical difference is that in humans and other land mammals, air is used both as the propellant that makes the vocal folds vibrate and as the medium in which the sounds are propagated," said study co-leader Coen Elemans, a University of Southern Denmark bioacoustics professor and expert in animal sound production. "In toothed whales, air is only used to drive the phonic lips that then, via tissue acceleration, generates a click that propagates through tissue in the nose and then into the water," Elemans added. "Both laryngeal and synringeal sound production rely on pressurized air from the lungs, but that will not work for deep-diving toothed whales because their lungs collapse due to high hydrostatic pressures at deep depths.