Cat Purring

A study published in October 2023 in the journal Current Biology has overturned a five-decade-old theory about how cats produce their purring sounds. Researchers led by Christian T. Herbst from the University of Vienna found that excised cat larynges can produce purring frequencies between 25 and 30 Hz without any muscle contractions or neural input. The discovery points to a previously unknown anatomical structure embedded in the vocal folds.

Herbst's team removed the larynges from eight domestic cats that had been euthanized due to terminal illness. They pressed the vocal cords together and pumped warm, humidified air through them. All eight produced self-sustained oscillations at typical purring frequencies.

The prevailing explanation since the 1970s held that cats actively contract and relax their laryngeal muscles about 30 times per second to purr. Measurements of electrical activity in laryngeal muscles in living cats supported this theory. "Anatomical investigations revealed a unique 'pad' within the cats' vocal folds that may explain how such a small animal, weighing only a few kilograms, can regularly produce sounds at those incredibly low frequencies—far below even than lowest bass sounds produced by human voices," Herbst says.

Karen McComb, an expert in animal behavior and cognition at the University of Sussex who was not involved in the study, says the new explanation "is much more in line with what we know about how vocalizations are produced in other vertebrates."

David Rice, a biomechanical engineer at Tulane University who has conducted research into the mechanics of cat purring, is not fully convinced. He says there is no guarantee that living cats' vocal cords behave the same way as the surgically removed cords. Just looking at excised larynges, he says, is "akin to removing the mouthpiece from a wind instrument and analyzing its sounds in isolation."

In May 2025, a team at Kyoto University's Wildlife Research Center published separate findings in PLOS ONE linking purring behavior to genetics. Yume Okamoto and colleagues studied 280 domestic cats and found that cats with the short-type androgen receptor gene were reported to purr more by their owners than those with the long-type gene. The team compared domestic cat DNA with 11 other Felidae species and found the long-type version exists only in domestic cats. "When we called for participants, we were moved to receive responses from 265 cat owners from across Japan in just a single day," Okamoto says.

The genetic findings suggest cats raised by humans from kittenhood, typically purebred cats, may rely less on vocal communication for survival. Previous studies indicate that purebred cats are more likely to carry the long-type gene than mixed-breed cats. Many mixed-breed cats in the Kyoto study were rescued former strays.

Bonnie Beaver, a veterinary scientist at Texas A&M University, says purring has historically had a "nonscientific explanation." Few theories were ever tested, she says. The Vienna study is "a good step forward."

The findings complicate practical applications. A January 2025 study in the journal Animals by researchers at Utrecht University tested a method to stop cats from purring during cardiac auscultation. The technique involves grasping the cat's larynx from below while holding the stethoscope. The researchers found purring interfered with auscultation in 8.8 percent of 582 cats examined. The method had an 89 percent success rate in terminating purring.

Earlier research has suggested purring may have healing properties. A 2001 study recorded purrs from 44 felids including cheetahs, ocelots, pumas, and domestic cats. Every animal produced frequencies between 25 and 150 Hz, ranges that correspond to vibrational frequencies used in treatment for bone growth and fractures. No large-scale trials have investigated the effect on humans.

Herbst's team acknowledges their data do not fully reject the muscle contraction hypothesis. "The current understanding of cat purring is incomplete," Herbst says, "and warrants further research."