The sofa purr is often, correctly, read as contentment. Cats also purr when frightened, hurt, ill or asking for food. The sound is a flexible channel, not a happiness meter.

Kittens purr young, in dialogue with their mother. In adults the same kind of vocalization appears in rest, in social contact and, at times, as self-soothing under tension. Context and the rest of the body decide the reading.

The mechanism was long debated. A 2023 study in Current Biology showed that a cat larynx can produce low-frequency oscillations through an aerodynamic mechanism, with pads of tissue in the vocal folds. In the living animal the nervous system starts and regulates the behavior; an isolated larynx is not the whole story.

There is also a solicitation purr. Earlier work, also in Current Biology, described a high-frequency component close to a cry, which people hear as urgent. It is a signal to a carer, not proof that the cat is relaxed.

A loose posture, half-closed eyes and neutral ears go with comfort. A stiff body, hiding, changed breathing or refusal to eat require another interpretation, even if the ears catch a purr.

Claims that the frequencies heal bone remain hypotheses, not a demonstrated therapy. A sudden behavior change, pain, breathlessness or lethargy belong in a veterinary clinic, not in an article on feline communication.

Image: domestic cat on snow / Wikimedia Commons. An outdoor animal, not a clinical photograph of the larynx. Cropped to 16:9.

Source consulted: Domestic cat larynges can produce purring frequencies | Current Biology; Why do cats purr? | Cats Protection.