title: Dynamics of biosonar signals in free-swimming and stationary dolphins: The role of source levels on the characteristics of the signals.
abstract: The biosonar signals of two free-swimming Atlantic bottlenose dolphins performing a complex sonar search for a bottom target in San Diego Bay were compared with the biosonar signals of a dolphin performing a target discrimination task in a net pen in the same bay. A bite-plate device carried by the free-swimming dolphins supported a hydrophone that extended directly in front of the dolphin. A biosonar measuring tool attached to the bite plate measured the outgoing biosonar signals while the dolphins conducted sonar searches. Each of the free-swimming dolphins used different biosonar search strategy in solving the problem and the dolphins' biosonar signals reflect the difference in strategy. The dolphin in the pen stationed in a hoop while echolocating on a target 6 m away and reported if the indentation on a spherical target was directed toward it. The signals were parameterized by determining the peak-to-peak source levels, source energy flux density, peak frequency, center frequency, root-mean-square (rms) bandwidth, rms duration, and the Q of the signals. Some parameters were similar for the free-swimming and stationary dolphins while some were significantly different, suggesting biosonar signals used by free-swimming animals may be different than signals used by dolphins in a pen.
authors.affiliation: Hawaii Institute of Marine Biology, University of Hawaii, P.O. Box 1346, Kaneohe, Hawaii 96744, USA.
authors.forename: Whitlow W L
authors.initials: WW
authors.lastname: Au
authors.affiliation: National Marine Mammal Foundation, 2240 Shelter Island Drive, San Diego, California 92106, USA.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Martin
authors.affiliation: National Marine Mammal Foundation, 2240 Shelter Island Drive, San Diego, California 92106, USA.
authors.forename: Patrick W
authors.initials: PW
authors.lastname: Moore
authors.affiliation: National Marine Mammal Foundation, 2240 Shelter Island Drive, San Diego, California 92106, USA.
authors.forename: Brian
authors.initials: B
authors.lastname: Branstetter
authors.affiliation: Zoology Department, University of Hawaii, Honolulu, Hawaii 96822, USA.
authors.forename: Adrienne M
authors.initials: AM
authors.lastname: Copeland
mesh_terms: D000162:Acoustics / Q000295:instrumentation; D000818:Animals; D050681:Bottle-Nosed Dolphin / Q000502:physiology* / Q000523:psychology*; D004192:Discrimination, Psychological; D004455:Echolocation; D008297:Male; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013550:Swimming; D014159:Transducers; D014828:Vocalization, Animal