Dear Colleagues, We are happy to announce the publication of the following article in the Journal of the Acoustical Society of America.
"Transmission beam characteristics of a Risso's dolphin" by Adam B. Smith, Laura N. Kloepper, Wei-Cheng Yang, Wan-Hsiu Huang, I-Fan Jen, Brendan P. Rideout, and Paul E. Nachtigall. DOI: http://dx.doi.org/10.1121/1.4937752 Abstract: The echolocation system of the Risso’s dolphin (Grampus griseus) remains poorly studied compared to other odontocete species. In this study, echolocation signals were recorded from a stationary Risso’s dolphin with an array of 16 hydrophones and the two dimensional beam shape was explored using frequency-dependent amplitude plots. Click source parameters were similar to those already described for this species. Centroid frequency of click signals increased with increasing sound pressure level, while the beamwidth decreased with increasing center frequency. Analysis revealed primarily single lobed, and occasionally vertically dual-lobed, beam shapes. Overall beam directivity was found to be greater than that of the harbor porpoise, bottlenose dolphin, and a false killer whale. The relationship between frequency content, beam directivity, and head size for this Risso’s dolphin deviated from the trend described for other species. These are the first reported measurements of echolocation beam shape and directivity in G. griseus. [ http://dx.doi.org/10.1121/1.4937752] Aloha, -- Adam B. Smith Ph.D. Candidate Marine Mammal Research Program Hawaii Institute of Marine Biology University of Hawaii at Manoa
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