Summary
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1.
The echolocative skills ofPteronotus parnellii parnellii andEptesicus fuscus were studied by measuring their ability in avoiding stationary and moving obstacles.
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2.
The frequency, repetition rate, duration and amplitude of the orientation signals emitted by the bat during three phases of negotiation of obstacles were studied.
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3.
During the avoidance of obstacles, both species of bats systematically shorten the duration, increase the repetition rate, and decrease the amplitude of their emitted orientation signals as they approach, negotiate and pass the obstacles.
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4.
Flying at different speeds inside the flight room during the avoidance of obstacles,Pteronotus parnellii parnellii appropriately adjust their emitted CF frequency according to the flight speed to accurately compensate for the positively Doppler-shifted echoes.
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5.
The frequency of the FM signals emitted at high repetition rate byEptesicus fuscus shifts downward as the bat enters into the final phase of negotiation of the obstacles.
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6.
The significance of the change in parameters of emitted signals in relation to echolocation is discussed. Presumably, the increase in the repetition rate of sound emission and the shortening of the sound duration is to monitor rapid changes in obstacle positions. The decrease in sound amplitude is either due to the difficulty in producing loud short sounds at the end of a long-held breath or to appropriately adjust the echo amplitude into the optimal range of sensitivity of the bat's ears.
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Jen, P.H.S., Kamada, T. Analysis of orientation signals emitted by the CF-FM bat,Pteronotus p. parnellii and the FM bat,Eptesicus fuscus during avoidance of moving and stationary obstacles. J. Comp. Physiol. 148, 389–398 (1982). https://doi.org/10.1007/BF00679023
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DOI: https://doi.org/10.1007/BF00679023