Technically they are apparently waving the glottis back and forth at high speeds to vibrate the vocal folds! No rush of air required. It's a remarkably strange vocalization for a bunch of reasons - - purrs are lower frequency than anything a mammal that size ought to be able to produce, and lower frequency vocalizations tend to be associated with displays and territories where you're advertising based on size. But that's not generally what purrs are doing, so... why evolve this weird vocal ability?
(Incidentally, in humans within a gender [and probably more precisely within a particular hormonal profile], you cannot tell body size from the pitch of voice - - but humans sure think you can!)
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timeasmymeasure
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Date: 2019-04-22 03:44 am (UTC)(Incidentally, in humans within a gender [and probably more precisely within a particular hormonal profile], you cannot tell body size from the pitch of voice - - but humans sure think you can!)