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Natural Science Forum / Physics / Acoustics / August 2005Why cats walk and jump so quietly ?
Hi ... When I played with my cat today, suddenly I rasied up a question in my mind. Why cats walk and jump so quietly ? Does this relate to the pads on foot, the body flexibility .... etc ? When a 15lbs cat jumps up onto a table, sound should be generated, where does this sound go ? It seems stupid to ask these questions here, but I hope someone can give me hints on that. Nelson >Hi ... When I played with my cat today, suddenly I rasied up a question >in my mind. Why cats walk and jump so quietly ? Does this relate to the [quoted text clipped - 5 lines] > >Nelson I don't think so. I can walk and jump quietly on a hard floor wearing ski boots. It is all a question of coordination of the muscles. I suspect that cats are very good at this. d Pearce Consulting http://www.pearce.uk.com > Hi ... When I played with my cat today, suddenly I rasied up a question > in my mind. Why cats walk and jump so quietly ? Does this relate to the [quoted text clipped - 5 lines] > > Nelson Ever heard the expression "light on his feet"? Cats exemplify this. You can appreciate the difference more by sitting in some public place and watching people walk by. Some come down heavy on their feet, basically falling forward and catching themselves abruptly with a thud. Others cooperate with the floor, catching themselves lightly with their muscles flexed to cushion the step. With training and practice, a person can learn to walk nearly silently. A lot of it is spatial awareness; knowing exactly where the ground is so it doesn't catch your foot by surprise. Martial arts disciplines often teach this skill, but cats have it naturally. Of course, the things you mentioned are important too. It helps that their feet are nicely padded, they are extremely flexible, and that their muscles are very dense and strong for their weight. It's interesting to compare video of a cat and a tiger walking. 15 pounds or 300, they use the same techniques, with the same result. Cheers, Walt > Hi ... When I played with my cat today, suddenly I rasied up a question > in my mind. Why cats walk and jump so quietly ? Does this relate to the > pads on foot, the body flexibility .... etc ? When a 15lbs cat jumps up > onto a table, sound should be generated, where does this sound go ? Darwin at work. Noisy cats have long ago starved to death and left the gene pool. Millennia of evolution has done its work. Angelo Campanella Yes, I understand. But where does the sound go ? Does the cats'jump not excite the floor or table surfaces and make sound ? Angelo Campanella 提到: >> Hi ... When I played with my cat today, suddenly I rasied up a question >> in my mind. Why cats walk and jump so quietly ? Does this relate to the [quoted text clipped - 8 lines] > > Angelo Campanella >Yes, I understand. But where does the sound go ? Does the cats'jump not >excite the floor or table surfaces and make sound ? The sound doesn't happen because the impulse is spread out over a long enough period that it contains no audible harmonics. The same happens during landing as the ligaments in the leg soak up the energy. d Pearce Consulting http://www.pearce.uk.com >>Yes, I understand. But where does the sound go ? Does the cats'jump not >>excite the floor or table surfaces and make sound ? Dynamics. You seem to have confined your query to the falling-stopping phenomenon, so I will dwell on that. One can bring a moving body to rest in any number of ways; stopping it suddenly (hit a brick wall), or by excessive damping (falling into a swimming pool), or optimally by absorbing the momentum of the falling body over a period long compared to a cycle of the the lowest frequency sound that can be heard. Thus, if the cat can cause his deceleration to occur over a period longer than 1/10th of a second, the sounds created by his body and the (pliable) surfaces upon which he comes to rest will all be well below 10 Hz. Infra sound will be emitted, but the radiation efficiency of such surfaces is very small. If you are in a car with the windows closed, and a cat lands on the roof, then you might hear such a thump. It important that the momentum absorption be done at a uniform rate (constant deceleration) without jerks since each jerk can cause deceleration forces of higher frequencies that 10 Hz. Padded feet and excellent muscle tone in the cats arms, legs and torso can help. Cats don't get out of shape as far as I can tell. Does that help? Angelo Campanella > Yes, I understand. But where does the sound go ? Does the cats'jump not > excite the floor or table surfaces and make sound ? They do excite the floor, and cats make noises when they jump. I can hear them. The difference between cats and e.g. dogs is that cats don't bark, they retract their claws and they are smaller than most dogs. best regards Peter > Yes, I understand. But where does the sound go ? Does the cats'jump not excite the floor or table surfaces and make sound ? I remember when I was a young kid, maybe 7 or 8, "impressing" my Mum. My sister and I were jumping off her bed onto the floor, and I could land nearly silently by prolonging the landing, by kind of absorbing the impact of the fall over a long time, by suitably deforming my muscles on impact. My younger sister just went "clomp!" every time! Martin  SignatureM.A.Poyser Tel.: 07967 110890 Manchester, U.K. http://www.livejournal.com/userinfo.bml?user=fleetie >> Yes, I understand. But where does the sound go ? Does the cats'jump not >> excite the floor or table surfaces and make sound ? [quoted text clipped - 10 lines] > > Martin So...(someone please correct me if I'm thinking wrongly) a 15lb object landing on a table releases a certain amount of energy, which may or may not be converted into sound waves. The cat minimizes the amount of sound produced by landing in a manner that dissipates the energy in other ways. It absorbs some of the energy into its body (which would convert the energy to heat), and another portion is converted to sub-audible pressure waves in the table surface. There is a certain amount of actual sound created, but not nearly as much as if it had been a rock instead of a cat. Also, a jumping cat often lands in a crouch, using its body to absorb some of the audible energy that is generated. Amazing critters. I wish the two strays that like to have territorial yeowling matches outside my bedroom at night were more concerned with remaining unheard. Cheers, Walt > >> Yes, I understand. But where does the sound go ? Does the cats'jump not > >> excite the floor or table surfaces and make sound ? [quoted text clipped - 30 lines] > yeowling matches outside my bedroom at night were more concerned with > remaining unheard. And keep in mind, Walt, that there's a qualitative difference between 15 lbs of books and 15 lbs of muscle, bones, and fur. Even if you would do something so hideously inhumane as to splat the cat against the wall, the sound will still be low frequency, nearly inaudible sound, except for the hissing of one pissed off cat. <grin> Ron snip....snip > And keep in mind, Walt, that there's a qualitative difference between > 15 lbs of books and 15 lbs of muscle, bones, and fur. Even if you > would do something so hideously inhumane as to splat the cat against > the wall, the sound will still be low frequency, nearly inaudible > sound, except for the hissing of one pissed off cat. <grin> In light of your experience with high-intensity ultrasound, do you know if that "pissed off", hissing cat could produce 143dB SPL at 16KHz or thereabouts? Just wondering. :>) Angelo, > Noisy cats have long ago starved to death and left the gene pool. < My cat Bear is too fat to land softly, yet I assure you he's in no danger of starving! :->) Seriously, another reason this ability is useful for cats is it lets them jump from high places without breaking a leg. --Ethan >Hi ... When I played with my cat today, suddenly I rasied up a question >in my mind. Why cats walk and jump so quietly ? Does this relate to the [quoted text clipped - 5 lines] > >Nelson Cats walk quietly because they do not wear shoes. Puss'N Boots was a noisey cat I bet. Put shoes on a cat, especially wooden shoes, and I bet it won't be quite anymore. boB >Cats walk quietly because they do not wear shoes. Puss'N Boots was >a noisey cat I bet. > >Put shoes on a cat, especially wooden shoes, and I bet it won't be >quite anymore. Put your own wooden shoe (or boot) on a cat - firmly, while you're wearing it - and the cat will be quite noisy. Ken Plotkin |
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