Frequency-dependent echolocation beam pattern of the bottlenose dolphin.
Publikation/Tidskrift/Serie: Journal of the Acoustical Society of America
Förlag: Acoustical Society of America
Moore and others (2008) previously showed that bottlenose dolphins are capable of beam steering and controlling the vertical and horizontal widths of the echolocation beam. A follow-on study was performed using the same methods as the previous study, but with a younger animal and a higher resolution diamond-shaped hydrophone array for characterizing the beam. The dolphin performed a target detection task while stationed on a biteplate with targets placed up to 34 deg to either the left or right of the dolphin's longitudinal axis. The dolphin was capable of beam steering more than 28 deg to either side, which is a greater capability than previously reported and which exceeded the geometric coverage of the array. Frequency band-limited beam patterns suggested the presence of two beams, spatially separate from one another and which corresponded to higher and lower frequency energies. The finding is consistent with prior anatomical and acoustic evidence of two echolocation click sound sources in the delphinids. In addition, at low frequencies, a local minimum was observed at the center of the beam. The functional significance of the local minimum, if any, is unknown.
- Biology and Life Sciences
- ISSN: 1520-8524