What is Purring?
“An act of purring; the low vibrating sound made by a cat pleased or contented: a sound resembling this”
The Shorter Oxford English Dictionary.
Scientists divide the cat family into two groups. Big cats can roar, but small cats can’t. Big cats, like lions and tigers cannot purr properly. The Tiger will great you (if not hungry and about to eat you!) With a friendly ‘one way purr’ a sort of juddering splutter. Domestic and small cats can purr a two way purr. They purr as they inhale and exhale.
The Scientists have 2 different theories as to how a cat can purr.
The first theory is that the cat has an extra set of false vocal cords in their voice box, or larynx. These false vocal cords allow the cat to produce a soft rumbling noise for hours without even opening its mouth. This theory suggests that purring is very similar to heavy breathing, similar to snoring in humans. With every breath in and out the cat makes, the air passes over the false vocal cords and this makes the RRRRRRRRR noise of the purrrr and as the muscles of the larynx contact they cause the noise to be interrupted and vibrate.
The second theory suggests that the cats voice- box has nothing to do with the creation of the purring noise instead the purr is created by turbulence in the cat’s blood flow through its main veins. As the blood flow is restricted as it passes from its heart in to the cat’s chest this makes a swirling noise as it vibrates and this is amplified by the cat’s diaphragm. The noise produced passes up the cats windpipe to its sinus cavities in its skull where it resonates producing the purring sound. As the cat arches its back whilst purring this increases the pressure of the blood flow and therefore the purr is louder.
Why does a cat purr?
Although cats often purr when they are happy and contented it is true that this is not always the case. Cats may also purr when they are distressed or in pain. A cat will often purr when they wish to relax or wish for companionship. If a cat in pain is visiting a veterinary they may well purr because they are seeking the friendship of the vet and they need help.
Purring occurs first when kittens are only one week old and their mother is suckling them. She signals to her kittens that all is well and that they should drink her milk. When the kittens purr in reply she knows that the kittens are reaching her milk and that all is well. By purring to her kittens she is telling them that she is relaxed and it encourages them to feed.
The use of purring in adult cats (and between adults and humans ) is certainly secondary and is derived from this parent-offspring context.
Cats can train their besotted owners with their purr to do their bidding?
Cats use special pleading purr to get their owners to do their bidding research suggests.
By embedding a high-pitched “cry” into the lower tones of their purr, their purr can sound more urgent and plaintive. It has been suggested that cats may find that purring in this way gets their owners to respond to their “feed me” request quicker than by meowing at the besotted owners.
The cats pleading purr appeals to humans desire to nurture offspring. Studies have shown that cats purrs recorded while cats were actively seeking food were more urgent and less pleasant for people than non-solicitation purrs played at the same volume.
Not all cats use their purr in this way and it was found that cats in a one-one relationship with their owners were more likely to use this type of purr. Solicitation purring also appeared to be more common when cats were alone with their owners, and at antisocial times, such as early in the morning.