In complex biosonar scenes, the delay of echoes represents the spatial distribution of objects in depth. To avoid overlap of echo streams from successive broadcasts, individual echolocation sounds should only be emitted after all echoes of previous sounds have returned. However, close proximity of obstacles demands rapid pulse updates for steering to avoid collisions, which often means emitting a new sound before all of the previous echoes have returned. When two echo streams overlap, there is ambiguity about assigning echoes to the corresponding broadcasts. In laboratory tests of flight in dense, cluttered scenes, four species of echolocating bats exhibited different patterns of pulse emissions to accommodate potential pulse-echo ambiguity. Miniopterus fuliginosus emitted individual FM pulses only after all echoes of previous pulses had returned, with no alternating between long and short intervals. Pipistrellus abramus and Eptesicus fuscus alternated between emitting long FM pulse intervals to receive all echoes before the next pulse, and short intervals to update the rapidly changing scene while accepting partial overlap of successive echo streams. Rhinolophus ferrumequinum transmitted CF/FM pulses in alternating short and long intervals, usually two to four closely spaced sounds that produced overlapping echo streams, followed by a longer interval that separated echo streams. Rhinolophus is a statistical outlier from the three FM species, which are more similar to each other. The repeated overlap of CF/FM echo streams suggests that CF components have a distinct role in rejection of clutter and mitigation of ambiguity.
ACCEPTED MANUSCRIPT
RESEARCH ARTICLE|
01 January 2019
Biosonar interpulse intervals and pulse-echo ambiguity in four species of echolocating bats
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Neuroethology
James A. Simmons
,
James A. Simmons
*
1
Department of Neuroscience, Brown University, Providence, RI, USA
*Author for correspondence: James_Simmons@brown.edu
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Shizuko Hiryu,
Shizuko Hiryu
2
Faculty of Life and Medical Sciences. Doshisha University, Kyotanabe, Japan
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Uday Shriram
Uday Shriram
3
Program in Biotechnology, Brown University, Providence, RI, USA
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James A. Simmons
*
1
Department of Neuroscience, Brown University, Providence, RI, USA
Shizuko Hiryu
2
Faculty of Life and Medical Sciences. Doshisha University, Kyotanabe, Japan
Uday Shriram
3
Program in Biotechnology, Brown University, Providence, RI, USA
*Author for correspondence: James_Simmons@brown.edu
Received:
31 Oct 2018
Accepted:
07 Mar 2019
Online ISSN: 1477-9145
Print ISSN: 0022-0949
Office of Naval Research
(N00014-12-1-0339)
Japan Society for the Promotion of Science
(JP16H06542)
J Exp Biol jeb.195446.
Article history
Received:
31 Oct 2018
Accepted:
07 Mar 2019
Currently Viewing Accepted Manuscript - Newer Version Available
15 Apr 2019
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Citation
James A. Simmons, Shizuko Hiryu, Uday Shriram; Biosonar interpulse intervals and pulse-echo ambiguity in four species of echolocating bats. J Exp Biol 2019; jeb.195446. doi: https://doi.org/10.1242/jeb.195446
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