That low, rattling vocal register known as vocal fry—the Washington Post points to Kim Kardashian and Katy Perry as two examples of celebrities who have such gravelly voices—has proven a polarizing topic, with some insisting it's sexy, while others call it grating. But while the appeal of vocal fry in humans may be subjective, scientists say there's an actual practical use for it for another species. In new research out of Denmark published Thursday in the journal Science, researchers reveal that toothed whales, which include orcas, sperm whales, dolphins, and porpoises, have at least three vocal registers, just like people do: a "normal" voice, a falsetto, and said vocal fry—"the first evidence of broad register use in any animal, besides humans," University of Southern Denmark voice scientist and study co-author Coen Elemans tells the Post.
Marine mammals such as whales often hunt way down in the ocean depths, in near-complete darkness, and so they rely on echolocation, which involves the reflection of sound waves, to "see" objects, including prey. Per the New York Times, scientists have long suspected that something in whales' nasal cavities helps create not only the echolocation "clicks" they make, but also their various other vocalizations, including grunts and higher-pitched whistles. Elemans' team found that whales do indeed have structures in their nose called phonic lips, which function much like a human's larynx, or voice box, and allow the whales to produce the sounds they make. The scientists discovered this by inserting endoscopes with tiny cameras into the nasal cavities of trained Atlantic bottlenose dolphins and harbor porpoises to record high-speed footage as the animals made sounds.
"They saw that the phonic lips would briefly separate and then collide back together, causing a tissue vibration that would release sound into the surrounding water," the Times notes. The researchers say that the whales mainly use the other two registers for general communication purposes, while the lower-register vocal fry comes in handy deep underwater as the whales are searching for prey, as it uses the least amount of air. "One thousand meters down, you have 1% of the air you had at the surface," explains study co-author Peter Madsen, a zoophysiologist at Denmark's Aarhus University. Elemans calls the vocal similarities to humans "striking," per the Post, while Andrea Ravignani, who co-wrote an op-ed on the study in Science, notes that the discovery was "quite unexpected and mind-blowing." (Read more discoveries stories.)