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Directionality of nose-emitted echolocation calls from bats without a nose leaf (Plecotus auritus)

Jakobsen, Lasse LU ; Hallam, John; Moss, Cynthia F. and Hedenström, Anders LU (2018) In Journal of Experimental Biology 221(3).
Abstract

All echolocating bats and whales measured to date emit a directional bio-sonar beam that affords them a number of advantages over an omni-directional beam, i.e. reduced clutter, increased source level and inherent directional information. In this study, we investigated the importance of directional sound emission for navigation through echolocation by measuring the sonar beam of brown long-eared bats, Plecotus auritus. Plecotus auritus emits sound through the nostrils but has no external appendages to readily facilitate a directional sound emission as found in most nose emitters. The study shows that P. auritus, despite lacking an external focusing apparatus, emits a directional echolocation beam (directivity index=13 dB) and that the... (More)

All echolocating bats and whales measured to date emit a directional bio-sonar beam that affords them a number of advantages over an omni-directional beam, i.e. reduced clutter, increased source level and inherent directional information. In this study, we investigated the importance of directional sound emission for navigation through echolocation by measuring the sonar beam of brown long-eared bats, Plecotus auritus. Plecotus auritus emits sound through the nostrils but has no external appendages to readily facilitate a directional sound emission as found in most nose emitters. The study shows that P. auritus, despite lacking an external focusing apparatus, emits a directional echolocation beam (directivity index=13 dB) and that the beam is more directional vertically (-6 dB angle at 22 deg) than horizontally (-6 dB angle at 35 deg). Using a simple numerical model, we found that the recorded emission pattern is achievable if P. auritus emits sound through the nostrils as well as the mouth. The study thus supports the hypothesis that a directional echolocation beam is important for perception through echolocation and we propose that animals with similarly non-directional emitter characteristics may facilitate a directional sound emission by emitting sound through both the nostrils and the mouth.

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Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Acoustic signals, Animal bioacoustics, Biosonar, Chiroptera
in
Journal of Experimental Biology
volume
221
issue
3
publisher
The Company of Biologists Ltd
external identifiers
  • scopus:85042023945
ISSN
0022-0949
DOI
10.1242/jeb.171926
language
English
LU publication?
yes
id
3c80f305-7e2f-4f47-88fe-40f1723c81df
date added to LUP
2018-03-07 08:58:20
date last changed
2018-05-29 11:22:04
@article{3c80f305-7e2f-4f47-88fe-40f1723c81df,
  abstract     = {<p>All echolocating bats and whales measured to date emit a directional bio-sonar beam that affords them a number of advantages over an omni-directional beam, i.e. reduced clutter, increased source level and inherent directional information. In this study, we investigated the importance of directional sound emission for navigation through echolocation by measuring the sonar beam of brown long-eared bats, Plecotus auritus. Plecotus auritus emits sound through the nostrils but has no external appendages to readily facilitate a directional sound emission as found in most nose emitters. The study shows that P. auritus, despite lacking an external focusing apparatus, emits a directional echolocation beam (directivity index=13 dB) and that the beam is more directional vertically (-6 dB angle at 22 deg) than horizontally (-6 dB angle at 35 deg). Using a simple numerical model, we found that the recorded emission pattern is achievable if P. auritus emits sound through the nostrils as well as the mouth. The study thus supports the hypothesis that a directional echolocation beam is important for perception through echolocation and we propose that animals with similarly non-directional emitter characteristics may facilitate a directional sound emission by emitting sound through both the nostrils and the mouth.</p>},
  articleno    = {171926},
  author       = {Jakobsen, Lasse and Hallam, John and Moss, Cynthia F. and Hedenström, Anders},
  issn         = {0022-0949},
  keyword      = {Acoustic signals,Animal bioacoustics,Biosonar,Chiroptera},
  language     = {eng},
  month        = {02},
  number       = {3},
  publisher    = {The Company of Biologists Ltd},
  series       = {Journal of Experimental Biology},
  title        = {Directionality of nose-emitted echolocation calls from bats without a nose leaf (Plecotus auritus)},
  url          = {http://dx.doi.org/10.1242/jeb.171926},
  volume       = {221},
  year         = {2018},
}