Journal of Comparative Physiology A

, Volume 178, Issue 2, pp 235–241 | Cite as

Integration time for short broad band clicks in echolocating FM-bats (Eptesicus fuscus)

  • A. Surlykke
  • O. Bojesen
Original Paper


Vespertilionid FM-bats (four Eptesicus fuscus and one Vespertilio murinus) were trained in an electronic phantom target simulator to detect synthetic echoes consisting of either one or two clicks. The threshold sound pressure for single clicks was around 47 dB peSPL for all five bats corresponding to a threshold energy of -95 dB re 1 Pa2 * s. By varying the interclick interval, ΔT, for double clicks it was shown that the threshold intensity was around — 3 dB relative to the threshold for single clicks at ΔT up to 2.4 ms, indicating perfect power summation of both clicks. A threshold shift of -13.5 dB for a 1 ms train of 20 clicks (0.05 ms interclick interval) confirmed that the bats integrated the power of the stimuli. At ΔT longer than around 2.5 ms the threshold for double clicks was the same as for single clicks. Thus, the bats performed like perfect energy detectors with an integration time of approximately 2.4 ms. This integration time is an order of magnitude shorter than that reported for bats listening passively for pure tones. In our setup the bats emitted sonar signals with durations of 2–3 ms. Hence, the results may indicate that while echolocating the bats integration time is adapted to the duration of the sonar emissions.

Key words

Bat Eptesicus Echolocation Energy detection Temporal integration 



automatic gain control


frequency modulated


peak equivalent sound pressure level


root mean square


standard deviation


standard error of mean


interclick interval


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Copyright information

© Springer-Verlag 1996

Authors and Affiliations

  • A. Surlykke
    • 1
  • O. Bojesen
    • 1
  1. 1.Center for Sound Communication, Institute of Biology, Odense UniversityOdense MDenmark

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