Cats also use many sounds to express themselves vocally. Scientists have identified about 100 distinctive cat vocalizations. These vocal sounds are grouped into three patterns—murmurs, vowels and strained or high-intensity sounds—based on how they are produced. The murmur patterns are sounds a cat makes while her mouth is closed; they include purring and the dulcet, trilling vocalizations that express greetings or acknowledgment. There are many theories as to why cats purr, and the mechanics of how they actually make the sound is still a mystery. Cats are able to purr in monotone in response to their mother licking them when they are two days old (this probably communicates to their mother that they are content and well fed).
As kittens mature, the purring begins to vary in speed, pitch, rhythm and volume, producing many types of sounds. Generally, purring is a sign of pleasure and contentment, although some cats who are ill, severely injured, in pain, frightened or giving birth often purr resonantly, perhaps as a way of asking for help. The vowel patterns cats make include different sounds, such as “meow” and its many variations, used by a cat to coax, demand, complain, inform and express surprise. Most of the chatty sounds made by Siamese are classified as vowel patterns.
The sounds are started while the cat’s mouth is open and finished when it is closed, and are used to communicate with other cats and with humans. Most cats develop a vocabulary of specific sounds that mean “please,” “no,” “food,” “dirty litter box,” “out,” “play” and many others that you can learn to understand if you listen closely. Generally, the more aggravated a cat becomes, the lower the pitch of the meow. Strained or high-intensity sounds are made with the mouth open and express anger or emotion. Used mostly for communicating with other cats, these include growling, snarling, hissing, spitting, yowling, screaming and the ritualistic mating cry.
Cats make these sounds when they are frightened, angry, mating, fighting or in pain. Each cat has her own particular vocabulary, the size of which will vary greatly depending on breed, sex and temperament. Siamese, Abyssinians and Oriental Shorthairs, for example, are known to be very talkative, while Persians tend to say very little.
Cats carry on conversations with their owners, their kittens and other cats. But undoubtedly, vocal communication reaches its pinnacle during the mating season. Many unneutered females become very noisy when they go into heat and call loudly and constantly to inform the opposite sex that they are ready to mate, while the males howl and caterwaul at night. Then there is the enchanting silent meow, where the cat opens her mouth and appears to meow, but no sound comes out. (The term was made popular in 1964 by Paul Gallico in The Silent Meow, a handbook written exclusively for cats, advising them on how to overpower a human family and discipline the family members.) Adult cats also do this. Although there are several theories as to the purpose of the silent meow, its meaning is known onlyto the cat who makes it.