A cat's purr is not just a sign of contentment, as biologists had previously assumed. Veterinarians and others have long known that cats also purr when giving birth, when gravely ill, or when recovering from injuries.
An interesting website called AnimalVoice.com cites a paper that was presented at the 2001, 142nd annual Acoustical Society of America, American Institute of Physics, International Conference. The title is "The Felid Purr: A healing mechanism?"
The article explains that all small cats, such as domestic cats and ocelots, and many of the large cats, such as lions, purr. And they purr at or near a particular frequency of vibration of 100 Hz, which has been shown to heal broken bones and other injuries in humans. Physicians, therapists, and trainers often use a metal plate, vibrating at 100 Hz, to help heal injuries and build new tissue.
The speculation is that cats use the vibration that causes the purring sound to heal themselves. Researchers cited the fact that cats heal easily from surgery, illnesses and traumas from which dogs would not recover.
Then the paper discusses many illnesses, such as some types of cancers that dogs have, that either do not occur or only very rarely occur in cats. It also gives statistics on many types of surgeries and traumas from which cats recover much faster than dogs.
It is very impressive, and the implication thoughout the paper is that the cat on your lap or pressed against your side, purring, just may be also healing you.
If the researchers are right, it is actually the vibration rather than the sound itself that heals. But as I mentioned in my last post, sound is a spectrum, not all of which is audible to humans.
The effect of the purr probably comes from the same part of the sound spectrum as the sub-bass vibrations I mentioned then. But the frequency is different, the rhythm is different, and so the effect is different.
I suggest going to this link and reading the article for yourself. Then you decide.
Meanwhile, for those of us who love cats, as if being loved by a cat were not blessing enough, now there's this one! Cats healing with sound. Imagine that!