Teddy Zagone, age 11, of Mundelein, I11., for his question:
HOW DOES A CAT PURR?
This is one of Andy's most popular questions, which means that lots of readers ask it all the time. Naturally the same old story tends to get boring, so even the most popular questions cannot be selected more than once in a great while. So, if you happen to be curious about cat purring, now is your chance to find out. This friendly offer will not be repeated for several years.
Humans and most animals have one set of vocal cords to do all their talking and singing, screaming and hollering. But the cats are more fortunate. Apparently they have two sets of vocal cords to produce two quite different types of sound.
One would expect our modern experts to be able to explain in precise detail exactly what goes on inside a purring cat. However, some are not positive and may dispute some of the details. But most of them agree that the following explanation is pretty close to the facts.
In the first place, vocal cords are flaps of skin attached to the walls of the throat, whether they belong to people, cats or other animals. Air breathed up from the lungs causes these vocal cords to vibrate like built in sounding boards. From here the air passes up to be modified and magnified by various curves, caves and muscles in the mouth.
A cat, as we know, tends to be a chatty creature with quite a wide vocabulary. Aside from an assortment of mews and meows, she can challenge rival cats with a resounding range of screams, shrieks and prolonged hollers commonly called caterwauling. These sounds, it is agreed, are produced by a set of everyday vocal cords situated low in her throat. Above them is her extra special set of vocal cords, which most experts agree is reserved for her soft, sweet purring sounds.
In any case, she is unable to use both sets of vocal cords at the same time. It seems that the everyday set must be silenced for the purring set to work. This usually happens when Miss Puss is relaxed. Then her breathing gently vibrates the upper set of vocal cords, causing the soft, sweet purring
A cat enjoys life to the fullest, but most of all she enjoys her periods of safe and comfortable relaxation. Such periods are even more enjoyable when she has a beloved human friend to stroke her soft fur. This, no doubt, is why she tends to run her purring motor when she is in a mood of blissful contentment.