for National Geographic News
Hungry house cats use an annoying but irresistible combination of sounds when they want to be fed, a new study has found.
The combo may explain why cat owners seem willing to fill food dishes at all hours rather than simply ignoring or ejecting the cat, noted study leader Karen McComb, a mammal-communications expert at the University of Sussex in the U.K.
When they're hungry, some cats blend their normal, pleasant purrs with whines comparable in frequency to the distress cries of human infants.
"They can sort of get away with solicitation that way rather than with just meowing, which might get them swept aside," McComb said.
Cats' Urgent Purrs
The concept of cat purring is strange by itself, McComb pointed out.
"Cats shouldn't really be able to produce low frequencies like that," because their vocal folds are too small.
Most animals make throat-based sounds using only their vocal folds. But cats can vibrate the muscles underneath their vocal folds very slowly, which produces the rumbling purr.
But that action leaves the inner edges of the vocal folds free to do something else.
By vibrating those inner edges while also purring, a cat can produce the higher-pitched distress call.
McComb's team and several volunteer cat-owners recorded straight purrs and purr-meow combinations in ten cats then played the recordings for 50 human listeners.
People judged the purr-meow combination to be more urgent and less pleasant than normal purring—even those participants who had never owned a cat.
Not all cats use this special purr combo, McComb noted. The sound seems to develop more often in cats that have one-on-one relationships with their owners.
That could be because the subtle sound is easier to overlook in cats living in larger households, she said. In those cases, a louder meow is more effective.
Overall, though, "things are very much on [the house cats'] terms," McComb said. "They seem to be quite successful as far as I can see."
Findings appear in the July 14 issue of the journal Current Biology.
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