Question: How do cats purr?

Susan Cartwright answered on 21 Jun 2015:

Purring is very characteristic of the cat family. Most cat species, except the big “roaring cats” (lion, tiger, jaguar, leopard) purr, as do a couple of species of genet (a more distant relative of the cat family), but nothing else. The key diagnostic of purring is that it is continuous: it doesn’t stop when the cat inhales, like most vocal noises. It’s also much lower frequency than the cat’s vocal sounds (miaows), which is why you can actually feel the cat vibrate if it is purring in your lap.

The mechanism of cat purring has been studied for a long time, with numerous different theories being advanced. However, it seems that the most likely idea is that it is caused by the muscles of the larynx (the voice box) rhythmically modifying the flow of air. In support of this idea, cats with paralysed larynxes can’t purr, and after surgery on the larynx the purr recovers when the voice does.