WASHINGTON: Recent findings suggest the skulls of some baleen whales capture acoustic properties that can capture the energy of frequencies and direct them to the ear bones San Diegtate University.
“What our contribution does is give us a window into how the world’s largest animals hear, by an odd mechanism no less. This research has driven home one beautiful principle: Anatomic structure is no accident. It is functional, and often beautifully designed in unanticipated ways,” said San Diego State University biologist Ted W. Cranford.
In recent years government regulators have been working to limit the amount of noise imposed on baleen whales. The offending sounds primarily come from commercial shipping, energy exploration, and military exercises. The sounds can be harmful because these whales produce vocalizations in the same frequency range as the man-made noises, interfering with their ability to communicate.
In the past little has been known about how baleen whales process sounds, making government rulings on the subject difficult to make. To make their findings a team of researchers built a highly-complex three-dimensional computer model of a baleen whale head and simulated how sound would travel through it.
There are two ways in which sound can reach the ear bone: it can either travel through the soft tissue (but this is ineffective if the sound waves are longer than the whales’ body) or vibrate along the skull in a process called bone conduction. The recent model showed that bone conduction was about four times more sensitive to low frequency sounds than the pressure mechanism; bone conduction was up to 10 times more sensitive to sounds of the lowest frequency.
“Bone conduction is likely the predominant mechanism for hearing in fin whales and other baleen whales,” Cranford said. “This is, in my opinion, a grand discovery.”
