The 25-Decibel Question: Why Do Cats Purr?

Have you every wondered why your cat purrs and feels like a motorboat of vibration? We explain the feline phenomenon.

Why do cats purr? By: Cassandra Gallegos-Moore

Cat purrs can sound like a light, soothing hum or a sputtering motorboat!

So, what makes them purr, and why do they do it? It can be as simple as contentment or include scientific theories.

What Is a Purr?

If you have ever held or stroked a cat while purring, you know what we’re talking about. For those that haven’t, purring creates a sound and a vibration from the cat. Cats make this sound and vibration combination by moving the muscles in the throat and diaphragm; there is no single or unique organ that produces the sound or the vibration.

Why Do They Do It?

Cats seem to purr when they are stroked, which we know they love or will push against our hands to get attention. I take this as a sign of contentment or satisfaction.  It turns out there are other ideas from scientists who believe purring is a function meant to heal or be social in cats.

The release of a chemical in the brain to relieve pain can be triggered by purring. This theory makes sense considering some cats purr while in labor.  Cats also purr when eating, sleeping or when in pain, and the volume, pitch and frequency can vary.

Purring can also be a cat’s way of being comforted. Some cats purr when they are stressed, such as a trip outdoors or a visit to the veterinarian. It can also be a sign that the cat is not harmful to anyone. Kittens are said to purr while feeding from a mother as a sign that they are receiving enough milk or that they are okay.

Yet another theory is possible: the Scientific American believes that cats may purr to stimulate bones and muscles without exerting a lot of energy. Since cats have very little bone abnormalities or illnesses compared to other animals, this theory seems pretty believable too.

How Loud Is a Purr?

As the title suggests, the average cat purrs at around 25 decibels. Cats can register a purr much lower or louder than that and might depend on the species. Cats can purr while inhaling or exhaling, but most cats in the wild purr when exhaling.

There is a world record in purring. No, seriously, there is! A cat from England named Smokey registered a purr of 80 decibels and as high as 92 decibels upon closer monitoring. A purr in this decibel range is as loud as a lawnmower or hair dryer! Smokey’s owner claims it can drown out a movie or make telephone conversations impossible when this kitty purrs up a storm.

Merlin is another kitty trying to beat Smokey’s world record and is currently out-purring him by 8 decibels. Read more here.

Other Animals That Purr

Purring isn’t just for the kitties says Benjamin L. Hart, DVM, PhD, distinguished professor emeritus at the University of California, Davis, School of Veterinary Medicine. Dr. Hart explains that cats that roar cannot purr, and cats that purr cannot roar. Other animals that can purr or make similar vibrations include raccoons, guinea pigs, mongooses and hyenas.

 


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