title: Echolocation signals and transmission beam pattern of a false killer whale (Pseudorca crassidens).
abstract: The echolocation transmission beam pattern of a false killer whale (Pseudorca crassidens) was measured in the vertical and horizontal planes. A vertical array of seven broadband miniature hydrophones was used to measure the beam pattern in the vertical plane and a horizontal array of the same hydrophones was used in the horizontal plane. The measurements were performed in the open waters of Kaneohe Bay, Oahu, Hawaii, while the whale performed a target discrimination task. Four types of signals, characterized by their frequency spectra, were measured. Type-1 signals had a single low-frequency peak at 40 +/- 9 kHz and a low-amplitude shoulder at high frequencies. Type-2 signals had a bimodal frequency characteristic with a primary peak at 46 +/- 7 kHz and a secondary peak at 88 +/- 13 kHz. Type-3 signals were also bimodal but with a primary peak at 100 +/- 7 kHz and a secondary peak at 49 +/- 9 kHz. Type-4 signals had a single high-frequency peak at 104 +/- 7 kHz. The center frequency of the signals were found to be linearly correlated to the peak-to-peak source level, increasing with increasing source level. The major axis of the vertical beam was directed slightly downward between 0 and -5 degrees, in contrast to the +5 to 10 degrees for Tursiops and Delphinapterus. The beam in the horizontal plane was directed forward between 0 degrees and -5 degrees.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Hawaii Institute of Marine Biology, University of Hawaii, Kailua 96734, USA.
authors.forename: W W
authors.initials: WW
authors.lastname: Au
authors.forename: J L
authors.initials: JL
authors.lastname: Pawloski
authors.forename: P E
authors.initials: PE
authors.lastname: Nachtigall
authors.forename: M
authors.initials: M
authors.lastname: Blonz
authors.forename: R C
authors.initials: RC
authors.lastname: Gisner
mesh_terms: D000818:Animals; D004455:Echolocation / Q000502:physiology*; D005260:Female; D008962:Models, Theoretical; D014907:Whales / Q000502:physiology*