Space-age scanners show how whale’s hearing is affected

Washington, Nov 25 ( Space-age scanners are making sense of how sounds generated by navy sonar might affect the hearing of whale – or if they hear it at all.

The type of large industrial sized X-ray scanners that National Aeronautics and Space Administration (NASA) uses to detect flaws in a space shuttle’s behemoth solid fuel rockets is now allowing scientists to peek inside the giant head of a whale.

The scans are providing detailed 3-D replicas of a whale’s hearing anatomy using a breakthrough method developed by Ted Cranford, marine biologist sponsored by the Office of Naval Research (ONR) and the Chief of Naval Operations Environmental Readiness Division.

Using a simulated model of a male beaked whale’s head, Cranford’s team at San Diego State University (SDSU) and University of California at San Diego (UCSD) has unveiled data that suggests mid-frequency active sonar sounds are largely filtered, or “muffled”, before reaching the animal’s ears.

The findings also suggest that higher frequencies used by whales to hunt prey are heard at amplified levels without any dampening.

“Even though these findings are promising, our next step is to reproduce the study with a similar species for which hearing tests are available, such as the bottlenose dolphin,” Cranford said.

“If we obtain like results, it will help to validate this new discovery.”

The innovative approach integrates advanced computing, outsized X-ray CT scanners, and modern computational methods (developed by Petr Krysl at UCSD) to generate the reproductions in minute detail.

The simulation, also referred to as a ‘finite element model’ or FEM, accurately describes the interactions of sound with the whale’s hearing anatomy.

It also forecasts and analyses incoming sound received at the ear and provides a description of how different characteristics combine to create movement throughout the ear, says a SDSU release.

“The simulation technology is powerful because it provides a means to look at a broad range of species, from whales to fish, for which we may not otherwise be able to study hearing,” said ONR program manager Michael Weise.