The interaction of outgoing echolocation pulses and echoes in the false killer whale's auditory system: evoked-potential study

J Acoust Soc Am. 2004 Jun;115(6):3218-25. doi: 10.1121/1.1707088.


Brain auditory evoked potentials (AEP) associated with echolocation were recorded in a false killer whale Pseudorca crassidens trained to accept suction-cup EEG electrodes and to detect targets by echolocation. AEP collection was triggered by echolocation pulses transmitted by the animal. The target was a hollow aluminum cylinder of strength of -22 dB at a distance from 1 to 8 m. Each AEP record was obtained by averaging more than 1000 individual records. All the records contained two AEP sets: the first one of a constant latency and a second one with a delay proportional to the distance. The timing of these two AEP sets was interpreted as responses to the transmitted echolocation pulse and echo, respectively. The echo-related AEP, although slightly smaller, was comparable to the outgoing click-related AEP in amplitude, even though at a target distance as far as 8 m the echo intensity was as low as -64 dB relative to the transmitted pulse in front of the head. The amplitude of the echo-related AEP was almost independent of distance, even though variation of target distance from 1 to 8 m influenced the echo intensity by as much as 36 dB.

Publication types

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

MeSH terms

  • Acoustic Stimulation
  • Animals
  • Audiometry, Evoked Response / methods
  • Discrimination Learning / physiology
  • Dolphins / physiology*
  • Echolocation / physiology*
  • Evoked Potentials, Auditory / physiology*
  • Female
  • Form Perception / physiology