Kittens purr a few days after birth to let the mother cat know where her kittens are and attract attention to feeding her baby. Cats purr for this reason throughout their lives; cat owners notice their cats will purr close to eating time. However, this is only one way a cat uses purring as part of their everyday lives.
Purring is also an instinct and a way for a cat to communicate and self-soothe. A study done in 2009 found “that cats can conceal a cry within their purr that triggers a nurturing instinct in their owners, similar to the cries of a human baby.”
A cat can also adapt to noises depending on the response from people, i.e., if the cat belonged to a deaf owner – they would be more likely to purr than meow since the owner would be able to feel the cat communicating.
Purring comes from the cat’s voice box (larynx); the glottis is dilated and constricted when cats breathe rhythmically and rapidly. The purring sound happens when the air vibrates over the larynx.
Finally, a 2001 study found that domestic and big cats, including cheetahs and pumas, use purring at frequencies that can provide pain relief and bone repair.