Popular English writer Terry Pratchett in his book "the cat's face best described the nature of the cat: Name one animal that the food is not what it benefits, protects the house or loudly chirp, and because, after eating, it goes happy and purrs".

Why cats purr

Purring is one way cats communicate. It is given to them almost from birth. The two-day kittens, still not able to meow, already being unable to purr. So they communicate with the mother while sucking milk, giving her the signal their good health. Often you can hear a purring response from the cat.

With age, the range of reasons why animals produce these sounds, is expanding. Cats purr when they want to show their appreciation. For example, if you are happy to see its master after a long separation. If the animal is frightened, it can also sound like. Thus it calms himself, just as people are humming happy songs in a stressful situation. The cat who went to their relatives, can purr, showing his friendly attitude.

There are cases where terminally ill cats purr, understanding that they have not long to live. This is the final sounds that may indicate excitement of the animal or, conversely, euphoria.

How cats purr

The initiator purring is a Central nervous system of the cat. The animal is making to this effort, everything happens spontaneously.

During the first experiments it was found that the nerve impulse causes vibration of the vocal cords and the diaphragm in turn pushes them through the air. As a result, in the cat's throat formed a purring sound. However, the reliability of the studies failed to prove, because animals at this time was immobilized.

More accurate results have shown scientists from the United States. They conducted experiments in vivo, using the microphones high sensitivity. They managed to prove that during the inhalation and exhalation of the cat the air passes through the two folds located in the larynx. They are also called false vocal cords. The vibration of these folds and causes purring.

The person is not able to repeat such a mechanism of communication. Unlike cats, people are able to make sounds only during expiration. On the inhale, the vocal cords close tightly.