Talk:Purr

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Contents 1 Citation request near the beginning of the article 2 Cellular level etc. 3 Why Cats Purr 4 TONAL? 5 purring humans 6 Bone density 7 a lion purring? 8 Is purring related to respiration? 9 Contentment Hypothesis 10 larger cat species can only purr during the exhale ??? 11 Reference for current theory of purring 12 Copyrighted Text 13 Remark about tigers needs clarification 14 Chemicals released when they purr? 15 confused meaning 16 references 17 Effect on humans Section doesn't make any sense 18 Reason for Purring - Medical Treatment? 19 Add audio 20 Unclear text removed 21 Other Animals That Purr? 22 Big cats high pitched? 23 Nice, but 24 Raccoons purr too! 25 Cat purring recording 26 The "Why Felines Purr" section

[edit] Citation request near the beginning of the article

There's no need to cite a source for the fact that cats can meow while purring. All you need to do to verify is spend some time around cats. This is a very common behavior. Requesting a citation here is like requesting a citation for "Cats have fur".

Agreed - I've seen it plenty of times. I've removed "Purring may have medical significance" from the intro as it's really unclear what this could refer too (and there's no reference to support it). --163.1.176.254 17:57, 25 May 2007 (UTC)

Well, I found this scientific study: "How Cats Purr. 1991. Sissom D.E.F., Rice D.A., Peters G. Journal of Zoology 223: 67-78.

Abstract: We measured purring in unrestrained intact pumas, cheetahs and domestic cats. Domestic cats, Felis silvestris f. catus, purr at a frequency of 26.3 +/- 1.95 (S.D.) Hz. The frequency at mid-expiration exceeds that at mid-inspiration by 2.4 +/- 1.3 Hz. Purring frequency for individuals does not change with age. Purring can occur simultaneously with other vocalization. Two-channel acoustic measurements confirm that the primary mechanism for sound and vibration production is a centrally driven laryngeal modulation of respiratory flow. The diaphragm and other muscles appear to be unnecessary for purring other than to drive respiration."

So it seems that it finding a citation is possible. Also, they give us the exact frequency, 26.3 Hz, and its standard deviation, 1.95, which tells us that 95% of all cats purr between 22.4 and 30.2 Hertz. Speciate 22:40, 8 July 2007 (UTC)

Well, assuming that the distribution is Gaussian it would be. But frequencies can only take positive values, while a Gaussian distribution would also include negative values, so the distribution would probably be more likley to be log-normal (or maybe Erlang or F or Landau or something), in which case the 95% confidence interval would be difference from the Gaussian bounds. I'd say if Sissom et al don't say what the confidence interval is then we can't put any values into the article without knowing the which distribution they saw. —Preceding unsigned comment added by 59.167.60.198 (talk) 04:41, 11 November 2007 (UTC)

Also, the article currently says that all cats purr with a frequency in the range 22.4 to 30.2 Hz, which is wrong even if the distribution is Gaussian. Anyone want to fix this sentence up with something that is correct? Replacing "all" with "most" would be start, but I think even putting the range as 20 to 30 Hz would be accurate enough for most people without too many decimal points obscuring the fact being put across. —Preceding unsigned comment added by 59.167.60.198 (talk) 04:46, 11 November 2007 (UTC)

I know that I feel emotional healing when I am close to my purring cat. Once when he was purring strongly, he pushed his nose firmly against the vein in my wrist. I actually ceased to hear the purr and felt it throughout my body. It was strange.Islenya (talk) 12:51, 7 January 2008 (UTC)

[edit] Cellular level etc.

I've removed "In light of the comparisons, a growing theory is that the purring of cats promote healing on the cellular level". The sentence too vague to have any medical meaning (we are told it is 'beneficial to healing') and 'healing on a cellular level' suggests that purring directly interacts with diseased cells. Neither is supported by the reference; it also does not belong in the "why cats purr" section. Instead I'm putting something like "The calming effect of cat's purring has been suggested as a therapy in mental illness and other disorders". Claims that low frequency sound directly influence some aspect of cellular health are not generally scientifically accepted, and good evidence is required (not a page from an advocate group) before they appear here.

Similarly, "Purring may also reduce pain, help a wounded cat to heal, or even help to keep a cat's bones strong". The reference cited did NOT measure any of these things, only the frequency of purring. Contrary to the reference, no research has been carried out linking bone healing and low frequency sound - a search on both pubmed and Scopus returns zero results for the terms "purring AND bone".

--163.1.176.254 17:49, 6 April 2007 (UTC)

Found more reference to bone healing -

"give birth ... and this may be to reduce the pain and also assist post-natal healing". Again, unsupported by the reference. -163.1.176.254 18:03, 25 May 2007 (UTC)

"The calming effect of cat purring has been suggested as a therapy in mental illness and other disorders." this is not specific enough in my opinion, it does not specify weather it is benifical to the cat or to humans.—Preceding unsigned comment added by 124.197.54.130 (talk • contribs)

[edit] Why Cats Purr

I like the fact the article doesn't assume cats generally purr to show it is happy but backs it up with noting it generally comes with other expressions like raised tail and closed eyes. Strictly these don't necessarily show the cat's enjoyment either. However, there is some additional evidence that purring is mostly a sign of pleasure. I would like to add that cat owners easily observe the fact that a purring cat will be a lot less likely to run or walk off from your presence as it would if you did something it didn't like. A purring cat does not act to remove any stimuli that might be negative. - Chris 14:16 GMT 14th February 2007

—The preceding unsigned comment was added by 194.42.125.16 (talk) 14:16, 14 February 2007 (UTC).

[edit] TONAL?

would somebody please explain how a 27 hertz vibration can be described as "tonal"????? why does the intro paragraph describe purring as "tonal" ? ladies and gentlemen this DOES NOT MAKE SENSE. seriously.128.119.232.102 04:21, 8 November 2005 (UTC)

[edit] purring humans

I am a human and i can purr... I do it somehow by concetrating on the muscles close to the ear, have to close my eyes when i do it... people are sometimes freaked out about it :D Foant

Perhaps so, but do you use the same mechanism your cat does? ww 19:18, 15 Feb 2005 (UTC)

Doubtless he doesn't. I love purring and "talking" back to my cats. If you're a cat-lover and no one's around to see you make a fool of yourself, try it sometime. It's like the repetition games children play. Find a "talky" cat, and repeat any noises it makes as accurately as possible. Most of the time the cat will continue making noises at you, and sometimes they get very interested in this unusual human who can speak.

P.S. Is there any chance an audio recording of a cat's purr could be added to wikipedia? -Kasreyn

Why not? Foant 16:47, 22 Apr 2005 (UTC)

I can do the same thing as you Foant, at least I think so :P It's not the same way a cat does it, I still focus on muscles near my ears (although I don't have to close my eyes). I think it has something to do with closing part of your oesophagus and blowing through it.. sort of like a controlled burp. splintax ^(talk) 14:36, 24 October 2005 (UTC)

I dont know actually... But when cats purr you can feel the muscels moving if you put your hand on them. Foant

How I purr: I say a German "r" (voiced uvular fricative), just with a lower frequency, and then voiceless. Not really like the voiceless uvular fricative, as that one usually has a high, hissing pitch, instead I manage to do a slow vibration with the same rear part of the tongue (The voiced version of this is called uvular trill). This also works when breathing in. The difference to cats: Cats can purr with mouth closed, I can't. Ah well .... cats are better than the rest of us. But it's a nice experience as it mixes concentration and relaxation. --84.115.129.76 11:05, 2 December 2005 (UTC) (unci)

[edit] Bone density

Cats purr at 27 - 44 hertz, and exposure to similar sound frequencies is known to improve bone density in humans.

Any chance of citing a source for that, please? I don't doubt it, but it caught my attention and I'd like to know more about it.

This has me wondering about the implications for long-duration space flight.

Secondly, I note that a line indicating that cheetahs can purr was removed a while ago. There's a link to a .wav file on this page that claims to be the sound of a cheetah purring. Loganberry (Talk) 02:41, 11 July 2005 (UTC)

I've re-added the cheetah. Someone was over-eager with deleting the phrase because it said that cheetahs did roar and purr, but they can't roar. Instead of correcting it, the person deleted the whole phrase: that's sloppy work. I've also added a source for the frequency thing, though I don't know if that's what the person who wrote that used; I didn't write it. Lupo 07:17, August 30, 2005 (UTC)

Both cheetahs and pumas purr but don't roar. This is because, although they are large in size and thus usually counted among big cats, they are genetically closer to small cats (and, indeed to each other) than to the other big cats. I am not adding this info myself, as I am unsure how this correlates with the article's statement that "whilst small cats can purr either during inhale or exhale, larger cat species can only purr during the exhale". -- Milo

I have no information about cheetahs, but there is a large literature of the American wilderness which repeatedly refers to mountain lions (or catamounts or pumas or ...) roaring. We need more, and more credible, information on the intermediate cats (jaguars, pumas, ...). Anyone know a zoo keeper? Is anyone on WP a zookeeper? ww 07:02, 16 October 2005 (UTC)

Jaguars are "intermediate"? They, along with tigers, lions, and leopards, are all in the genus Panthera, AKA the roaring cats. I do wonder, however, about the snow leopard (not related to true leopards, but considered one of the seven big cats). As for pumas, at best, they might have gained a sound similar to the Panthera roar through convergent evolution, as they are most definitely closer to small cats in the evolution tree. I recall reading that pumas have an extremely loud purr, which may be related to the issue. (Even if not, it probably deserves mention in an article about purring!) -- Milo

I disagree with Ephemeral life's 11 October edit. Although I lack the knowledge to gauge the scientific accuracy of the formerly linked article, I would like to point out that his edit was at least sloppy, as he retained the mentions that purring can "help a wounded cat to heal" and "help to keep a cat's bones strong", merely removing any semblance of scientific explanation or references to back up these claims. I would like to request that a more qualified person attempts to determine the scientific veracity of these claims, and depending on this either (A) returns the deleted reference, (B) removes the claims althogether, or (C) returns the reference with a disclaimer that it is an unproved theory, just like the various theories on HOW cats purr, one section above. -- Milo

[edit] a lion purring?

I would swear on any suitable ( to whosoever was swearing me in) tome that I saw a lioness purring in a zoo... it was audible form ~ 30 feet... does my memory play games with me?

I beleive this has come up before, and if I remember correctly, some, if not all, big cats such as lions, purr, but only when exhaling. I think...

Seconded. IIRC lion purring is rarer, but long established.

[edit] Is purring related to respiration?

The article seems to imply that we do not know how or why cats purr.

I've intuitively thought that it might have something to do with breathing -- that it might be similar to inhaling and exhaling at a high rate, in order to more efficiently deliver oxygen, instead of taking deep, long breaths, which requires more energy and lung pressure. But this is purely intuition.

See updated "How felines purr" for explanation of mechanism. --Sonelle 17:04, 10 October 2005 (UTC)

[edit] Contentment Hypothesis

The article seems to imply that purring has been incorrectly been associated (by humans) with a cat's happiness or contentment. I call this the "Contentment Hypothesis".

Where did the idea of purring and contentment originally come from, and what evidence is availble for and against the "contentment hypothesis"?

Does purring come before or after contentment? Could purring itself be what leads to contentment, rather than the other way around?

Is there any evidence that endorphins or other chemicals are released into the cat's bloodstream during purring? That could explain why cats seem happy while purring, while at the same time, explain why some frightened or injured cats purr.

Do cats purr when playing by themselves, or only when being pampered by their owners? The vibration's healing effect presumably affects not just the cat but anyone closeby, so purring could be the cat's way of saying "I like you, stay healthy."

Maybe I'm just being over-romantic, but I think it makes sense evolutionarily for a creature to want to promote its benefactors' health. Or its childrens' - note that some classical ways of pleasing a cat, such as rubbing its tummy, are pleasing to it because they associate them with kittens (who rub against the tummy when crawling under it to suckle).

An alternate theory is that humans like the purring sound, and so bred their pets to use it more :) -- Milo

Almost as plausible is that cats consider humans useful, and have bred humans to like purring, which they were doing anyway. Rpresser 18:39, 4 April 2006 (UTC)

Rpresser, And how is it that you think cats haven't done just that? There's clearly a good deal going on there that we miss. Consider only Fritz Lieber's Spacetime for Springers for one explanation of the obscure. When they learn to talk, maybe...

Uh...to put it gently, the burden of proof is not on Milo's end here.

Milo's point reminds me a great deal of flatcats, from Heinlein's Rolling Stones. His account is rather more clearly put, and who didn't dream of hearing a flatcat purr lo those many years ago? ww 03:37, 2 July 2006 (UTC)

I have a book called Catwatching (can't remember the author, but it can be retrieved) where it is suggested that cats purr both to solicit and reciprocate companionship. I have a kitten, and she purrs when you stroke her, but also purrs quite strongly when she deigns to sit near you and is feeling relatively sleepy or relaxed. If you don't do anything, she stops purring, falls asleep or goes away. If you stroke her, it continues.

Of course, I can't prove this, but I can find the bits from Catwatching about purring and so on. Does this sound of use? Jaz Mcdougall 01:03, 14 December 2006 (UTC). Forgot to sign- whoops!

[edit] larger cat species can only purr during the exhale ???

"Whilst small cats can purr either during inhale or exhale, larger cat species can only purr during the exhale."

Given that this statement a) is contradicted by the explanation of how cats pur and that b) the reference is a page explaning how Pumas (a larger cat species) purr, I have removed this statement to the talk page here until such time as someone can find suitable references to back it up. --Sonelle 17:04, 10 October 2005 (UTC)

According to the San Diego Zoo: http://www.sandiegozoo.org/animalbytes/t-smallcat.html

...big cats can’t purr continuously. They can only purr when they breathe out. The purr is interrupted when the cat breathes in. As a result, some big cats make a noise keepers refer to as a "chuffle.”

I have not found a specific research paper on the matter yet.[Ikmar 19:54, 30 October 2005]

[edit] Reference for current theory of purring

I've been looking to find a reference for the current larynx theory of purring. While I haven't been able to find a copy of the article, it was written by Lea Strogdale and John Delack, published in a 1997 issue of Cornell University's Animal Health Report. Can anyone find this article and verify the reference? My university's online index doesn't contain it. --Mcpusc 09:57, 8 November 2005 (UTC)

Stogdale L, Delack JB. Feline purring. Compendium on Continuing Education for the Practicing Veterinarian 1985; 7: 551, 553.

Reprinted in: Voith VL, Borchelt PL (eds). Readings in Companion Animal Behavior. Trenton: Veterinary Learning Systems, 1996; 269-270.

[edit] Copyrighted Text

I've removed the following text from the article, which is copied almost verbatim from The Straight Dope:

Mother cats may use purring to call their kittens to nurse. Unable to see, hear or smell very well the kittens can feel the vibrations of their mother's purring.

LVC 09:21, 26 December 2005 (UTC)

If a point is worth making, rewording is sufficient to avoid copyright problems. In this case, I seem to recall having seen this as an explanation of purring from an ethologist. Sorry, can't come nay closer than that as a citation. ww 03:30, 2 July 2006 (UTC)

[edit] Remark about tigers needs clarification

The entry currently says that tigers can purr, but only in one direction. I have no idea what "only in one direction" means in reference to purring. Can someone edit this to clarify?

Tigers can only make a purring noise while exhaling, not while inhaling. Domestic cats can purr continuously through both inhalation and exhalation. (I'll let someone else work this into the section) Rpresser 22:12, 15 April 2006 (UTC)

[edit] Chemicals released when they purr?

Hi. This might be stupid, but I've heard that cat-like creatures release a pleasure drug into the blood-stream when they purr. This might be the reason that they purr when they're injured - to decrease the pain. I've heard this on National Geographic. Once again, sorry if it's stupid. (by 07:39, 27 June 2006 SmileyMan)

Not a stupid comment. Much is obscure about purring as you can imagine. There are several chemicals (some hormones, some neurotransmitters, etc) in humans which are known to be secreted in some circumstances. The internal chemicals whose membrane receptors are used by opiates are an example. We don't understand these, or most such cellular interactions very well. And, since cats can't speak of their internal states, humnas are, oddly, easier experimental animals. You may find that journalists (including National Geographic productions) are more willing to speculate about the meaning of some research findings than they really should. ww 17:59, 27 June 2006 (UTC)

Hmmm, although I have no academic training in how and why cats purr, from my own background in biology and neuroscience I will posit that the chemicals cause the purring, not the other way around. If they are released, they are released by the nervous system in conjunction with the activation of purring, and lead to other bodily responses associated with the physiological conditions needed whenever purring occurs. In other words, purring is an efferent (from the brain) response, not an afferent (to the brain) stimulus. Whatever causes purring will also cause this chemical's release, whether it be endocrine (into the blood) or purely neurological. (To be geeky about it, the "purr center" in a cat's brain that innervates the nerves responsible for the mechanical act of purring will also innervate nerves which release (or activate another circuit which eventually releases) these chemicals, which may or may not actually be (but probably are) released.)

So the idea that these "pleasurable" or pain-killing chemicals (endorphins) are associated with purring is sound and even likely to occur, but the idea that purring serves as stimulus in a causal role for pain releif through chemical pathways just doesn't fit with what is known about these chemicals. 76.81.218.167 02:10, 19 March 2007 (UTC)

[edit] confused meaning

I've attempted to preserve the sense apparently meant in the 2nd para of How felines purr. The phrasing is now better, but the sense is still confused. Do cats have two vocal cord sets as the editor implies? I've left it in, but I'm not easy about it. In addition, many of the references seem to be to an article from an industrial magazine from B&K. Great company, I've used their stuff, but they're an engineering company, not a zoologicla one. I'd believe the article on the measurements, but much of it is speculation as neerly as I can make out. Is there something the B&K article used as a source about the effect of particular vibration frequencies on healing and such? I think we need it here. ww 04:23, 2 July 2006 (UTC)

[edit] references

Sorry to be pedantic, but the article contains five references to footnotes, but there are only four footnotes. What/where is footnote five? PatrickHadfield 15:09, 24 October 2006

As you see, Footnote3 is evil. Actually there are only three footnotes. saimhe 18:31, 24 October 2006 (UTC)

Converted to WP:FN format. Is it better? saimhe 18:44, 24 October 2006 (UTC)

[edit] Effect on humans Section doesn't make any sense

I have removed some errors from the "Effect on Humans" section that were in direct conflict with the citation. The citation is also not an acceptable reference. The entire section is highly questionable. What does the relative constancy of several cat's purrs have to do with the "effect on humans"? And what does how do the "harmonics" of 25Hz have substantial energy? That is pseudo-scientific babble that makes wikipedia seem like a silly website. —The preceding unsigned comment was added by 24.177.112.82 (talk) 03:39, 29 December 2006 (UTC).

There is considerable evidence that things we find soothing and relaxing, like a cat's purr, can reduce blood pressure and have long term benefits on human health. I've often heard that cat owners liv(statistically significant) longer lives than non cat-owners, although I don't have time or motivation to actually look up the research. My point is, the writer may have done a poor job explaining or citing the evidence, but don't dismiss the health benefits of pets on humans as pseudo-science just because of your own skepticism.

[edit] Reason for Purring - Medical Treatment?

The article speculates (without references) that cats purr when they need attention, such as medical treatment (because apparently they purr sometimes when injured - something coincidentally I have never observed). Why would a cat purr in the wild if it needs medical treatment? First, they can't give medical treatment to each other, and second, cats are solitary. 204.112.156.246 18:26, 29 December 2006 (UTC)

Not all cats are solitary. Having a signaling mechanism to indicate stress or injury, for example, between a kitten and mother, could definitely serve an evolutionary purpose. However, I find it hard to believe that evolution could select for a single type of signal (purring) to express both injury and contentment. This seems problematic to me. On the other hand, an "I need attention" signal could be used by both happy and sick cats alike...although this would be more of a plea for help than a "distress signal," as the article seems to suggest. With that said, I've never noticed my cats purring when they're upset, scared, or sick. So yeah I agree, sources would be nice... 76.81.218.167 01:36, 19 March 2007 (UTC)

[edit] Add audio

It'll be good if someone can upload a *purring* sound of a feline. That could provide more info, as expected out of a reader.

Mugunth 04:58, 2 February 2007 (UTC)

I can have a go if you like. I have cats and I'm sure I can record them purring. Is uploading a sound the same as uploading an image? Think outside the box 09:53, 14 February 2007 (UTC)

[edit] Unclear text removed

The author states in "How Felines Purr" section of the article that the mechanism for purring is unknown and identifies two theories (vocal cord manipulation, "...another area of soft tissue or muscular tissue in the neck or torso...") for how cats make the purring noise. However, in the paragraph right below the statement is made that "Cats that roar lack the purring vocal cords, and use the vocal cords in charge of roaring and growling instead, making a noise similar to growling when they purr." That statement assumes one of the two theories to be validated which is not the case and also contradicts itself. I altered the text to something less confusing. "Cats that roar seem to lack the mechanism for purring and in situations where purring cats purr cats that roar make a noise similar to growling. As a result, the two sounds are often confused." --Mychair 17:56, 22 April 2007 (UTC)

[edit] Other Animals That Purr?

I've had pet guinea pigs all my life, and they purr somewhat like cats do. They purr while they're being petted, and they'll also make a brief purring noise sometimes when startled. I'm sure there are probably other animals out there that purr as well. So, what other kinds of animals are known to purr, and is their purring related to the purring of cats? 71.61.233.43 01:14, 22 May 2007 (UTC)

Raccoons can purr. I once had a juvenile raccoon follow me and a group of hikers to a rest spot on a trail. While sitting there, the raccoon cuddled up against one of the women in the group and began purring. It sounded exactly like a cat. --Michael Daly (talk) 16:23, 25 December 2007 (UTC) ... I just noticed that someone previously added something on this at the bottom of the page - consider this confirmation. MD

[edit] Big cats high pitched?

I see a lot of unsubstantiated claims of purring frequency as high as 150 Hz. Since domestic cats purr at 26.3 Hz, these higher ranges must refer to the other feline species. But since they are bigger, one would expect them to purr lower, not higher, right? Therefore I have removed all reference to the higher pitches, pending a legit source (not one of those "purring cures bone disease" BS ones). Speciate 22:55, 8 July 2007 (UTC)

[edit] Nice, but

This is a nice, fun to read article. How much of it is fact and how much of it is just interesting reading? I'm not asking to whack out stuff. Don;t misunderstand. More references exists?Botrag 18:17, 14 July 2007 (UTC)

[edit] Raccoons purr too!

I had an opportunity to hold and play with a raccoon kit recently, and was surprised to find that it purrs! Sounds just like a cat, although it only purrs on exhaling. You can hear a recording of a raccoon purr at http://www.fcps.edu/islandcreekes/ecology/raccoon.htm (follow the link in the Additional Media section)Starfiremb 11:10, 3 August 2007 (UTC)

I have a cat, and I don't believe they purr when they're nervous or in pain —Preceding unsigned comment added by 213.181.226.21 (talk) 23:33, 20 September 2007 (UTC)

[edit] Cat purring recording

For me this site catsleep.com has been very helpful so have a look at it and I love to hear what others think. —Preceding unsigned comment added by Nockturn (talk • contribs) 17:54, 6 February 2008 (UTC)

It's a commercial site with very little information and that the same sort which was removed from this article as unsourcable credibly some time ago. The special frequencies of cat purring speeds healing thing. There's not much WP contnet there. The cat recording may be very good, but I didn't check it. Best, I expect, that one get an actual cat. ww (talk) 09:41, 5 June 2008 (UTC)

[edit] The "Why Felines Purr" section

I added a charitable "citation needed" to the highly speculative last para here, although feel deletion would have been better (I'm not a regular contributor to this article so will leave it to someone else to decide... I feel it really detracts from an otherwise well-written and credible piece). Señor Service (talk) 17:12, 24 May 2008 (UTC)

yeah, the last paragraph is ridiculous —Preceding unsigned comment added by 98.216.106.173 (talk) 18:47, 26 May 2008 (UTC)

However, cutting out any mention of the fact that cats purr when happy seems to be going too far, don't you think? --207.176.159.90 (talk) 00:49, 5 June 2008 (UTC)