Nobody is entirely sure how a cat purrs. The best current answer involves a neural oscillator in the brain firing 25 times a second. Cats also purr when injured, dying, and giving birth, which ruins the happiness theory.
The Cat Purr Frequency Myth: Where the 25 Hz Healing Claim Really Came FromCat purr frequency sits around 25 Hz, and that single number spawned a healing myth. Here is who measured it, who misread it, and what the trials show.pudgycat.io