In Darlene Ketten's laboratory, studies are directed at understanding how the ears of marine animals, particularly whales and dolphins, are able to hear and use underwater sounds. The marine mammal is examined using biomedical microimaging techniques such as computerized tomography (CT) and magnetic resonance imaging (MRI) to study auditory systems from a wide range of species and to produce mathematical and three-dimensional computer models of marine ears.
Darlene Ketten (right) and colleague extracting ears from a stranded humpback.
Information from the scans and information obtained from dissection allow us to create three-dimensional anatomical models of the marine mammal's head and model how the ear processes sound. The models allow us to estimate hearing abilities for rare and endangered species, like blue whales, that cannot be tested by normal methods. During our investigations, we have learned about the extraordinary hearing range of baleen whales, detecting a dozen octaves compared to the eight that humans can detect.
We have also found that toothed whale species have different hearing ranges suited to their respective habitats. Using computer simulations also lets us determine how whale ears withstand rapid pressure changes during dives and how underwater noise affects hearing. Because of the close relationship between what an animal hears and the sounds it produces, our work is linked closely with Petr Tyack's and William Watkins's research on vocalization and behavior and Michael Moore's research on the effects of pollutants and disease on marine mammals.
