It's created from the larynx, also known as the soundbox. The purr is a result of the movement of laryngeal muscles. When these muscles move, they constrict and dilate the glottis, part of the larynx. The glottis surrounds the vocal cords, and every time the cat breathes in or out, the air vibrates, making the sound we call a Purr. Although scientists are pretty sure of what creates a purr, they are still wondering what leads your cat to purr. 1. Healing, also known as the Purr Therapy 2. Calling for attention 3. Communicating their emotion 4. Greeting.