Toothed whales turned their vocal fry into a hunting superpower
For fishing 6,000 feet deep, whales need deep voices.
You absolutely know vocal fry when you hear it. From Britney Spears’ chart-topping 90s hit Baby, One More Time, to Kim Kardashian’s immediately recognizable voiceovers, this low, nasal way of speaking or singing is pretty much everywhere in pop culture.
It’s even found in the deepest depths of the ocean. A study published March 2 in the journal Science found that toothed whales have evolved an air-driven nasal source of sound that operates at different vocal registers.
[Related: Noise pollution messes with beluga whales’ travel plans.]
Like humans, toothed whales (sperm whales, orcas, belugas, etc,) have at least three vocal registers. The vocal fry register produces the lowest tones, the chest register produces a normal speaking voice, and the falsetto register produces higher frequencies.
“During vocal fry, the vocal folds are only open for a very short time, and therefore it takes very little breathing air to use this register,” said study co-author Coen Elemans, voice scientist at the University of Southern Denmark, in a statement.
Some toothed whales can dive over 6,000 feet deep to catch fish. While hunting in these deep and murky waters, they use short, powerful, ultrasonic echolocation clicks to find, follow, and catch their prey. They can produce up to 700 clicks per second and it works like sonar to use sound to locate objects.
When whales are over 3,000 feet deep, their lungs collapse to avoid compression sickness. The remaining air is held in the nasal passages inside of the skull, which provides small but sufficient airspace for the whales to produce echolocating sound.
While echolocating, they pressurize air in their nose and let it pass structures called phonic lips. These lips vibrate the same way that human vocal folds do and their acceleration creates sound waves that travel through the skull and up to the front of the head. Toothed whales make a wide variety of sounds for complex social communication in addition to echolocation.
[Related: A baby orca sparks a glimmer of hope for an endangered group of whales.]
“And this air-economy makes it especially ideal for echolocation. During deep dives, all air is compressed to a tiny fraction of the volume on the surface,” co-author Peter Madsen, a whale biologist at Aarhus University in Denmark, said in a statement. “Thus vocal fry allows whales access to the richest food niches on earth; the deep ocean.”
Previously, scientists believed that toothed whales used their larynx to make sounds like other mammals, but around the late-1980s, it became clear that they actually use their noses to produce sound. For this study, the team used endoscopes to see what is going on inside their noses and found that toothed whales have evolved an air-driven sound production system in their nose. The techniques used for this study took almost a decade to develop, including filming how the phonic lips vibrated.
“While vocal fry may be controversial in humans and may be perceived as everything from annoying to authoritative, it doubtlessly made toothed whales an evolutionary success story,” Elemans said.