Smith, AdamAdamSmithKloepper, LauraLauraKloepperYang, Wei-chengWei-chengYangHuang, Wan-HsiuWan-HsiuHuangJen, I-FanI-FanJenP Rideout, BrendanBrendanP RideoutNachtigall, PaulPaulNachtigall2019-05-232019-05-232016https://scholars.lib.ntu.edu.tw/handle/123456789/410079https://www.scopus.com/inward/record.uri?eid=2-s2.0-84954156595&doi=10.1121%2f1.4937752&partnerID=40&md5=ed29ff0b4aae224f038d243206938917The 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. ? 2016 Acoustical Society of America.Acoustics; Mammals; Sonar; Beam directivity; Bottlenose dolphins; False killer whales; Frequency contents; Frequency dependent; Sound pressure level; Source parameters; Transmission beams; Dolphins (structures); anatomy and histology; animal; echolocation; female; head; physiology; regression analysis; sound detection; toothed whale; Animals; Dolphins; Echolocation; Female; Head; Regression Analysis; Sound Spectrographyjournal article10.1121/1.4937752]2-s2.0-84954156595