Dynamics of biosonar signals in free-swimming and stationary dolphins: The role of source levels on the characteristics of the signals

J Acoust Soc Am. 2016 Mar;139(3):1381-9. doi: 10.1121/1.4944636.

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.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acoustics / instrumentation
  • Animals
  • Bottle-Nosed Dolphin / physiology*
  • Bottle-Nosed Dolphin / psychology*
  • Discrimination, Psychological
  • Echolocation*
  • Male
  • Signal Processing, Computer-Assisted
  • Sound Spectrography
  • Swimming*
  • Transducers
  • Vocalization, Animal*