Why do cats purr?
Purring is a low-frequency vibration cats make to soothe, signal, and maybe self-heal.
It happens in the throat, not the chest
A purr is not a sound the lungs make on their own. The cat’s brain fires a steady rhythmic message to the muscles around the larynx, which open and close the glottis dozens of times a second.
Because the muscles interrupt the breath on both the inhale and the exhale, the purr is nearly continuous, unlike a meow, which only rides the outgoing breath.
What a purr is for
Purring is easy to read as pure happiness, but cats also purr when frightened, in pain, or near death. The common thread is that purring tends to appear when a cat wants to calm itself or draw a caregiver closer.
Some cats add a higher, more urgent frequency to a ‘solicitation purr’ when they want feeding, a sound researchers found people find harder to ignore.
The healing hypothesis
This idea is intriguing but unproven, the frequencies overlap with therapeutic ranges, yet no one has shown a cat’s purr actually speeds its own healing. For now it stays a hypothesis worth testing, not a settled fact.