Cats purr through a unique mechanism involving their larynx (voice box) and the rapid contraction of muscles in their throat. When a cat breathes, the glottis (the opening between the vocal cords) rapidly opens and closes at a rate of about 20 to 30 times per second, causing air to vibrate over the vocal folds and produce the characteristic purring sound during both inhalation and exhalation
. This process is controlled by a "neural oscillator" in the cat's brain, which sends signals to the laryngeal muscles to twitch quickly, creating the vibrations that result in purring
. The sound is continuous and rhythmic, unlike other vocalizations such as meowing, which occur only during exhalation. Purring starts early in kittens, serving as a communication signal to their mother that they are okay and to encourage bonding
. Adult cats purr for various reasons including contentment, communication, self-soothing, and even healing. Purring has been linked to pain relief and bone healing due to the low-frequency vibrations it produces
. In summary, cats purr by rapidly contracting muscles in their larynx to rhythmically open and close the glottis, producing vibrations as air passes through during breathing, all controlled by neural signals from the brain
