This is how a whale hears

Washington, Feb 4 : Researchers from San Diego State University and the University of California have discovered a new pathway for sound entering the head and ears in an unusual whale species by utilising computer models.

The scientist made use of advances in Finite Element Modeling (FEM), Computed tomography (CT) scanning, and computer processing, to imitate the effects of underwater noise on Cuvier's beaked whale.

These technologies have made it possible for the researchers to simulate the environment and anatomy of a Cuvier's beaked whale when a sonar signal is sent out or received by the whale.

This study triggered by Dr Cranford of San Diego State University may prompt future research that could end years of speculation about the effects of underwater sound on marine mammals.

FEM is an engineering technique that is used, for example, to simulate the effect of an earthquake on a building. The effect of forces such as an earthquake, or in this case noise vibrations, can be accurately predicted by putting in the exact geometry and physical properties of a building.

Ten years back, Dr Cranford started the research into Cuvier's beaked whales, when he undertook the first ever CT scan of a large whale. This made the researchers to obtain the very complex anatomic geometry of a sperm whale's head.

"I think that the methods developed for this research have the potential to revolutionize our understanding of the impact of noise on marine organisms," said Dr Cranford.

It has been thought since 1968, that noise vibrations travel through the thin bony walls of toothed whales' lower jaw and onto the fat body attached to the ear complex.

However, the research displayed that thin bony walls do not transmit the vibrations. In fact they enter through the throat and then pass to the bony ear complex via a unique fatty channel.

The research was published in the recent issue of the Institute of Physics' Journal, Bioinspiration and Biomimetics.

ANI