Look who is talking - cat communication through sound.
At midnight in the alley
A tomcat comes to wail,
And he chants the hate of a million years
As he swings his snaky tail.
(Don Marquis, 'The tomcat')
Cats use a variety of ways to communicate. When cats want to get a message through to another cat, they prefer to use body language, but sound is also an option. Cats will growl and hiss when they want an enemy off their turf, but if this fails, nothing says 'go away' like a set of sharp claws and teeth. Cats will scream or yowl when they are combat or in pain (which is sometimes the same thing), or if they are angry or scared. And a female in heat will use a calling sound to let tom cats know she is in the mood for love. However, while sound is used for intra-cat communication, cats seldom talk to other animals, apart from humans who cats sometimes regard as felines who are too unintelligent to grasp the nuances of body language.
For humans, cats have developed the familiar all-purpose 'miaow'. It would be nice, as Lewis Carroll once remarked, if cats had a different miaow for a 'yes' and a 'no'. However, as many cat owners will tell you, cats can get their message across quite clearly if you are prepared to listen. It's just that Lewis Carroll was not observant to notice that all 'miaows' are not the same. A cat's vocal apptus differs from that of humans and is not designed for making speeches. As Mildred Moelk points out in her article 'Vocalizing in the house-cat; a phonetic and functional study' : "The animal uses the inhaled, as well as the exhaled, breath for vocalizing and does not appear to use the tip of the tongue at all, while its vowel variations are due, for the most part, due to changes in throat-tension rather than to modification of the position of the jaws and other mouth-parts.' So a cat uses breathing in as well as breathing out to make sounds, which are modified by pressure in the air supply. When you consider this is the same mechanism that produces bagpipe music, it explains a lot.
Some of the most common sounds by which a cat converses with humans are:
Chirrup - a friendly greeting, somewhere between a meow and a purr (with rising inflection; familiar to most cat owners)
Trill - a very friendly greeting sound often given by satisfied cats - for example cats returning from outdoors and jovially announcing that they are delighted to see their human companions, especially as these humans should be now leaping into action and loading the food bowl with the cat's preferred delicacies.
Meow - general-purpose attention seeking sound used by adult cats to communicate with owners, kittens, or others of limited mental faculties - a sort of feline 'oi! you'.
Purr - contentment, relaxation, also to comfort itself if in pain (cats in extremis may purr); a loud purr invites close contact or attention. But there is more to purr than that which can be fit into a short description. You can find out about why and how cat purrs in an article on this site: "The purrsuit of happiness. Why (and how) cats purr.".
Squawk - surprise, shock (somewhat strangled sound)
Chatter - excitement, frustration e.g. when prey is out of reach or escapes (involves rapid teeth-chattering jaw movements). It can be heard during play time.
Soundless Meow - when the cat open her mouth but no sound comes up. Some believe that the sound is very high pitched, too high for our hearing. It is a very gentle and polite way of asking for something if the non-vocal body language of intense staring has failed to telepathically get the message through.
A distressed or threatened cat will hiss, growl or scream at humans as well as at other cats. In all cases these are clear signals to back off and get out of the cat's face. A harassed mother cat will even use this signal to tell kittens that playtime is over. A scream might be an urgent warning that the cat is in pain, and in general, sharp sounds signify distress or impatience, with the possibility of claws being deployed in the near future. Medium pitch sounds are for for less urgent situations such as suggestions that it is time to start serving more food. A 'meow' emitted whilst purring usually means a contented cat, and more generally means 'pay attention to my body language and start figuring out what I want you to do.'
Like humans, cats build up their vocabulary as they get older. Kittens have a much smaller 'vocabulary', though they start purring on about their the second day of life. The next sound they make is a greeting sound which sounds like 'mhrn', and that comes along at about week three. From then onward a lot depends on the breed and environment. Cats which are talked to very often get the idea that humans are trying to communicate, and will talk back more readily than cats which don't have this encouragement. Many believe that some cat breeds (particularly Siamese and oriental cats) are more talkative. Siamese have a much wider range of pitch which gives them the upper hand in cat conversations. Burmese too are not shy about expressing themselves but British Shorthairs show true English reserve and are in general much quieter.
Of course cats are very observant and many will on occasion try imitating the amusing actions of their humans. This is also true with sounds. While cats seem to believe that most human vocalizations are irrelevant and can safely be ignored, they will on occasion alter the pitch and the length of a sound to produce something to which the human responds more readily . These 'sound diversions' will be very individual to a particular cat, and if a human tells you that their cat can talk they mean is that she can pronounce proper words. Generally this is what the owners want to hear rather that what the cat actually says. Saying that, there are now a number of videos on U-tube which play cat talk and some of them do sound extremely realistic. Have a look at these three: