ECE Seminar Speaker: Dr. Laura Kloepper

Abstract:
Sound is of utmost importance to odontocetes, and toothed whales and dolphins evolved a hypertrophied auditory system for the production and hearing of ultrasonic signals. As concern increases for the impact of anthropogenic noise on their ecology and behavior, the need for a basic understanding of sound production and hearing becomes paramount. Despite decades of research on the hearing and echolocation of odontocetes, several fundamental gaps in knowledge of their echolocation remain. This research aimed to fill these gaps using a combination of psychophysics, behavior, and acoustics with a false killer whale. This included investigating the impact of high-frequency hearing loss on echolocation discrimination performance and echolocation signal characteristics, characterizing the size and shape of the echolocation beam, and investigating active focusing in the echolocation beam during various echolocation tasks.

The data indicate that false killer whale modified its echolocation clicks to match its range of best hearing, but these changes in echolocation signals corresponded to a drop in echolocation discrimination performance. The size and shape of the echolocation beam was single-lobed, with most of the energy located between 20 and 80 kHz, but this beam size changed during echolocation. Irrespective of frequency, the false killer whale changed its beam size depending on the target distance and difficulty. These data are the first empirical data to directly show beam focusing in an odontocete, and suggest that the odontocete echolocation system is dynamic and capable of short and long term changes. These changes can occur in the echolocation click characteristics or echolocation beam shape and can allow odontocetes to adapt to various acoustic challenges in their environment.

Biography:
Laura Kloepper obtained her MS and Ph.D. in Zoology from the University of Hawaii at Manoa in April 2012. While at the Hawaii Institute of Marine Biology, Dr. Kloepper worked under Dr. Paul Nachtigall to measure the hearing and echolocation signals of laboratory and stranded whales and dolphins in Hawaii and around the world. Dr. Kloepper was awarded the NSF Postdoctoral Research Fellowship in Biology and is currently working with Dr. James Simmons at Brown University and Dr. John Buck at UMass Dartmouth to investigate bat biosonar performance using the Cramér-Rao Lower Bound and adaptive beamforming. Dr. Kloepper is also an avid triathlete.