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Scientists study how bones of baleen whales absorb sound waves

"What our contribution does is give us a window into how the world's largest animals hear, by an odd mechanism no less," said Ted W. Cranford.

By Brooks Hays
The skull of the fin whale scientists used to create their computer simulation. Photo by San Diego State University.
The skull of the fin whale scientists used to create their computer simulation. Photo by San Diego State University.

SAN DIEGO, Jan. 30 (UPI) -- The ability to communicate long-distance is key to the survival of baleen whales, a group of whales boasting the largest members of the animal kingdom on land and sea -- including blue whales, minke whales, right whales, gray whales and fin whales.

Despite the importance of their low frequency vocalizations, as a way to share information about feeding and mating opportunities, scientists still know relatively little about the whales' hearing process.

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But new research by scientists at San Diego State University and the University of California, San Diego, has offered new insight on how the bones of baleen whales absorb low frequency sound waves and direct them toward the ear.

This new information may prove vital as policy makers are called on to craft new rules about man-made noise in the ocean -- a factor many environmentalists blame for the shrinking numbers of certain baleen whale species.

As researchers explain, there are two main ways that animals absorb and deliver sound waves -- either via pressure waves that travel through soft tissue, or via what's called bone conduction.

To find out which method is most ideal for baleen whales, scientists recreated a virtual skull of a fin whale and simulated the process of sound absorption via complex computer modeling. The results showed that bone conduction -- which compresses and amplifies the sound waves -- was some 10 times as sensitive to the low frequency waves.

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"Bone conduction is likely the predominant mechanism for hearing in fin whales and other baleen whales," San Diego State University biologist Ted W. Cranford explained in a press release. "This is, in my opinion, a grand discovery."

"What our contribution does is give us a window into how the world's largest animals hear, by an odd mechanism no less," Cranford added. "This research has driven home one beautiful principle: Anatomic structure is no accident. It is functional, and often beautifully designed in unanticipated ways."

The study was published this week in the journal PLOS ONE.

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