investigator in San Diego ( aka “ Whale ’s Vagina ” ) have digitally recreated the entire head of a fin whale , break how these baleen colossus are able to hear : os vibration . Their skull have acoustic properties capable of capture the DOE of down frequencies . Thefinding , release inPLOS ONEthis week , help resolve a long - stand up mystery about one of the humans ’s largest and extremely inaccessible fauna .
Baleen whales can emit extremely low frequency vocalizations that travel far distance under water . But many of these are in the same oftenness mountain chain as serviceman - made noises from commercial shipping , energy exploration , and military exercises — which may confine how they communicate with each other about food or better half . But there ’s a lot we do n’t know about how baleen whales actually hear . Much of what we do know is generalise from anatomic study of their ears and profound playback experiment .
Using a unlike approaching , Ted Cranford from San Diego StateandPetr Krysl from University of California , San Diego , built a 3D computer model of a baleen heavyweight nous to simulate how sound travels through it . They based the skin , tongue , muscles , and everything in between on Adam - ray CT scan of a young fin whale ( Balaenoptera physalus ) who beached on Sunset Beach in Orange County . ( They used a gadget originally designed for Eruca vesicaria sativa motors . ) Using these scans , they applied “ finite component modeling ” ( pictured below ) to break the datum up into millions of tiny bits to track their various connections to each other . It ’s a bit like dividing the whale ’s read/write head into a serial of LEGO brick , Cranford explain in aSDSU release .
There are two ways for sound to reach the interlocked pinna bone bind to a hulk ’s skull : pressure level waves through diffuse tissue paper or vibration along the skull ( anticipate ivory conduction ) . pressing waves are uneffective if the sound waves are longer than the heavyweight ’s eubstance ; with bone conduction , on the other hand , farsighted wavelengths are overdraw as the skull vibrates .
When the duo simulated sound waves passing through the computerized skull , they were able to see how each miniscule part of the mind reply . And bone conduction , they observe , was about four times more raw to modest frequency phone than the pressure mechanism . In fact , for the lowest frequency used by louvre whales ( in the 10 to 130 Hz cooking stove ) , bone conductivity could be up to 10 time more sensitive .
We experience something similar when we ’re submerge in a swim syndicate . " Our ear are useless , but we still hear something because our head shakes under the pushing and pull of the sound waves expect by the water , ” Krysl explains in aUCSD release .
Cranford adds : “ Anatomic structure is no accident . It is useable , and often attractively designed in unforeseen ways . " Here ’s a very cool television show up the deformations and movement of the skull for a 250 Hz wave :
Images : SDSU ( top ) , Ted W. Cranford and Petr Krysl ( midway )
