Advertisement

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

Abstract

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 

Abbreviations

AGC

automatic gain control

FM

frequency modulated

peSPL

peak equivalent sound pressure level

rms

root mean square

SD

standard deviation

SE

standard error of mean

ΔT

interclick interval

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Algom D, Babkoff H (1984) Auditory temporal integration at threshold: Theories and some implications of current research. In: Neff WD (ed) Contributions to sensory physiology, vol. 8. Academic Press, New York, pp 131–159Google Scholar
  2. Andersen BB, Miller LA (1977) A portable ultrasonic detection system for recording bat cries in the field. J Mammal 58: 226–229Google Scholar
  3. Au WWL, Moore PWB, Pawloski DA (1988) Detection of complex echoes in noise by an echolocating dolphin. J Acoust Soc Am 83: 662–668Google Scholar
  4. Brown CH, Maloney CG (1986) Temporal integration in two species of Old World monkeys: Blue monkeys (Cercopithecus mitis) and grey-cheeked mangabeys (Cercocebus albigena). J Acoust Soc Am 79: 1058–1064Google Scholar
  5. Casseday JH, Erlich D, Covey E (1994) Neural tuning for sound duration: Role of inhibitory mechanisms in the inferior colliculus. Science 264: 847–850Google Scholar
  6. Dubrovskiy NA (1990) On the two auditory subsystems in dolphins. In: Thomas JA, Kastelein RA (eds) Sensory abilities of cetaceans. Plenum, New York London pp 233–254Google Scholar
  7. Gellerman LW (1933) Chance orders of alternating stimuli in visual discrimination experiments. J Genet Psychol 42: 206–208Google Scholar
  8. Griffin DR (1953) Bat sounds under natural conditions, with evidence for echolocation of insect prey. J Exp Zool 123: 435–465Google Scholar
  9. Hartley DJ (1992) Stabilization of perceived echo amplitudes in echolocating bats. I. Echo detection and automatic gain control in the big brown bat, Eptesicus fuscus, and the fishing bat, Noctilio leporinus. J Acoust Soc Am 91: 1120–1132Google Scholar
  10. Johnson CS (1968) Relation between absolute threshold and duration-of-tone pulses in the bottlenosed porpoise. J Acoust Soc Am 43: 757–763Google Scholar
  11. Johnson CS (1991) Hearing thresholds for periodic 60-kHz tone pulses in the beluga whale. J Acoust Soc Am 89: 2996–3001Google Scholar
  12. Kick SA (1982) Target detection by the echolocating bat, Eptesicus fuscus. J Comp Physiol 145: 431–435Google Scholar
  13. Kick SA, Simmons JA (1984) Automatic gain control in the bats sonar receiver and the neuroethology of echolocation. J Neurosci 4: 2725–2737Google Scholar
  14. Levitt H (1971) Transformed Up-Down methods in psychoacoustics. J Acoust Soc Am 49: 467–477Google Scholar
  15. Moore PWB, Hall RW, Nachtigall PE (1984) The critical interval in dolphin echolocation: What is it? J Acoust Soc Am 76: 314–317Google Scholar
  16. Moss CF, Simmons JA (1993) Acoustic image representation of a point target in the FM-bat, Eptesicus fuscus: Evidence for sensitivity to echo phase in bat sonar. J Acoust Soc Am 93: 1553–1562Google Scholar
  17. Møhl B (1986) Detection by a pipistrelle bat of normal and reversed replica of its sonar pulses. Acustica 61: 75–82Google Scholar
  18. Møhl B, Surlykke A (1989) Detection of sonar signals in the presence of pulses of masking noise by the echolocating bat, Eptesicus fuscus. J Comp Physiol A 165: 119–124Google Scholar
  19. Penner MJ (1978) A power law transformation resulting in a class of short-term integrators that produce time-intensity trades for noise bursts. J Acoust Soc Am 63: 195–201Google Scholar
  20. Plomp R, Bouman MA (1959) Relation between hearing threshold and duration for tone pulses. J Acoust Soc Am 31: 749–758Google Scholar
  21. Schmidt S, Thaller J (1994) Temporal auditory summation in the echolocating bat, Tadarida brasiliensis. Hearing Res 77: 125–134Google Scholar
  22. Simmons JA, Fenton MB, O'Farrell MJ (1979) Echolocation and pursuit of prey by bats. Science 203: 16–21Google Scholar
  23. Simmons JA, Freedman EG, Stevenson SB, Chen L, Wohlgenant TJ (1989) Clutter interference and the integration time of echoes in the echolocating bat, Eptesicus fuscus. J Acoust Soc Am 86: 1318–1332Google Scholar
  24. Simmons JA, Moffat AJM, Masters WM (1992) Sonar gain control and echo detection thresholds in the echolocatingbat, Eptesicus fuscus. J Acoust Soc Am 91: 1150–1163Google Scholar
  25. Stapells DR, Picton TW, Smith AD (1982) Normal hearing thresholds for clicks. J Acoust Soc Am 72: 74–79Google Scholar
  26. Supin AY, Popov VV (1995) Temporal resolution in the dolphin's auditory system revealed by double-click evoked potential study. J Acoust Soc Am 97: 2586–2593Google Scholar
  27. Surlykke A (1992) Target ranging and the role of time-frequency structure of synthetic echoes in big brown bats, Eptesicus fuscus. J Comp Physiol A 170: 83–92Google Scholar
  28. Surlykke A, Miller LA, Møhl B, Andersen BB, Christensen Dalsgaard J, Jørgensen MB (1993) Echolocation in two very small bats from Thailand: Craseonycteris thonglongyai and Myotis siligorensis. Behav Ecol Sociobiol 33: 1–12Google Scholar
  29. Suthers RA, Summers CA (1980) Behavioral audiogram and masked thresholds of the Megachiropteran echolocating bat, Rousettus. J Comp Physiol 136: 227–233Google Scholar
  30. Troest N, Møhl B (1986) The detection of phantom targets in noise by serotine bats; negative evidence for the coherent receiver. J Comp Physiol A 159: 559–567Google Scholar
  31. Viemeister NF, Wakefield GH (1991) Temporal integration and multiple looks. J Acoust Soc Am 90: 858–865Google Scholar

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

Personalised recommendations