Anyone with a cat knows the calm, low rumble of purring, but how does such a small animal make such a low sound?

New research suggests it boils down to a pad embedded in feline vocal cord folds.

That’s different than previously thought, which was that purring happened through a special mechanism, with cyclical contraction and relaxation of the muscles in the vocal folds within the larynx, and that it required constant control from the brain.

“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 [20 to 30 Hz, or cycles per second] — far below even than lowest bass sounds produced by human voices,” researcher Christian Herbst, a voice scientist from the University of Vienna, said in a university news release.

The findings, published online Oct. 3 in the journal Current Biology, aren’t an outright contradiction of the previous theory, but they are a clear indicator that the understanding of cat purring is incomplete, the researchers said.

A controlled laboratory experiment showed that the domestic cat larynx can produce these low-pitched sounds with a mechanism similar to the human “creaky voice.”

More information

The U.S. Library of Congress has more on how cats communicate with each other.

SOURCE: University of Vienna, news release, Oct. 4, 2023