Bottlenose dolphins project broadband echolocation signals for detecting and locating prey and predators, and for spatial orientation. There are many unknowns concerning the specifics of biosonar signal production and propagation in the head of dolphins and this manuscript represents an effort to address this topic. A two-dimensional finite element model was constructed using high resolution CT scan data. The model simulated the acoustic processes in the vertical plane of the biosonar signal emitted from the phonic lips and propagated into the water through the animal's head. The acoustic field on the animal's forehead and the farfield transmission beam pattern of the echolocating dolphin were determined. The simulation results and prior acoustic measurements were qualitatively extremely consistent. The role of the main structures on the sound propagation pathway such as the air sacs, melon, and connective tissue was investigated. Furthermore, an investigation of the driving force at the phonic lips for dolphins that emit broadband echolocation signals and porpoises that emit narrowband echolocation signals suggested that the driving force is different for the two types of biosonar. Finally, the results provide a visual understanding of the sound transmission in dolphin's biosonar.
References
1.
Aroyan
, J. L.
(2001
). “Three-dimensional modeling of hearing in Delphinus delphis
,” J. Acoust. Soc. Am.
110
(6
), 3305
–3318
.2.
Aroyan
, J. L.
, Cranford
, T. W.
, Kent
, J.
, and Norris
, K. S.
(1992
). “Computer modeling of acoustic beam formation in Delphinus delphis
,” J. Acoust. Soc. Am.
92
(5
), 2539
–2545
.3.
Au
, W. W. L.
(1993
). The Sonar of Dolphins
(Springer-Verlag
, New York
), p. 277
.4.
5.
Au
, W. W. L.
, Houser
, D. S.
, Finneran
, J. J.
, Lee
, W.
, Talmadge
, L. A.
, and Moore
, P. W.
(2010
). “The acoustic field on the forehead of echolocating Atlantic bottlenose dolphins (Tursiops truncatus)
,” J. Acoust. Soc. Am.
128
(3
), 1426
–1433
.6.
Au
, W. W. L.
, Kastelein
, R. A.
, Rippe
, T.
, and Schooneman
, N. M.
(1999
). “Transmission beam pattern and echolocation signals of a harbor porpoise (Phocoena phocoena)
,” J. Acoust. Soc. Am.
106
(6
), 3699
–3705
.7.
Au
, W. W. L.
, Moore
, P. W. B.
, and Pawloski
, D. A.
(1986
). “Echolocation transmitting beam of the Atlantic bottlenose dolphin
,” J. Acoust. Soc. Am.
80
, 688
–691
.8.
Au
, W. W. L.
, and Simmons
, J. A.
(2007
). “Echolocation in dolphins and bats
,” Phys. Today
60
(9
), 40
–45
.9.
Bérenger
, J. P.
(1994
). “A perfectly matched layer for the absorption of electromagnetic waves
,” J. Comput. Phys.
114
(2
), 185
–200
.10.
Cranford
, T. W.
(1988
). “Anatomy of acoustic structures in the spinner dolphin forehead as shown by X-ray computed tomography and computer graphics
,” in Animal Sonar: Processes and Performance
, edited by P. E.
Nachtigall
and P. W. B.
Moore
(Plenum Publishing Co.
, New York
), pp. 67
–77
.11.
Cranford
, T. W.
(1992
). “Functional morphology of the odontocete forehead: Implications for sound generation
,” Ph.D. thesis, The University of California
, Santa Cruz, CA
.12.
Cranford
, T. W.
(2000
). “In search of impulse sound sources in odontocetes
,” in Hearing by Whales and Dolphins
, edited by W. W. L.
Au
, A. N.
Popper
, and R. R.
Fay
(Springer-Verlag
, New York
), pp. 109
–156
.13.
Cranford
, T. W.
, Amundin
, M.
, and Norris
, K. S.
(1996
). “Functional morphology and homology in the odontocete nasal complex: Implications for sound Generation
,” J. Morphol.
228
(3
), 223
–285
.14.
Cranford
, T. W.
, Trijoulet
, V.
, Smith
, C. R.
, and Krysl
, P.
(2014
). “Validation of a vibroacoustic finite element model using bottlenose dolphin simulations: The dolphin biosonar beam is focused in stages
,” Bioacoustics
23
(2
), 161
–194
.15.
Finneran
, J. J.
, Branstetter
, B. K.
, Houser
, D. S.
, Moore
, P. W.
, Mulsow
, J.
, Martin
, C.
, and Perisho
, S.
(2014
). “High-resolution measurement of a bottlenose dolphin's (Tursiops truncatus) biosonar transmission beam pattern in the horizontal plane
,” J. Acoust. Soc. Am.
136
(4
), 2025
–2038
.16.
Finneran
, J. J.
, Mulsow
, J.
, Branstetter
, B. K.
, Moore
, P. W.
, and Houser
, D. S.
(2016
). “Nearfield and farfield measurements of dolphin echolocation beam patterns: No evidence of focusing
,” J. Acoust. Soc. Am.
140
(2
), 1346
–1360
.17.
Harper
, C. J.
, Mclellan
, W. A.
, Rommel
, S. A.
, Gay
, D. M.
, Dillaman
, R.
, and Pabst
D. A.
(2008
). “Morphology of the melon and its tendinous connections to the facial muscles in bottlenose dolphins (Tursiops truncatus)
,” J. Morphol.
269
(7
), 820
–839
.18.
Houser
, D. S.
, Finneran
, J. J.
, Carder
, D. A.
, Van Bonn
, W.
, Smith
, C.
, Hoh
, C.
, Mattrey
, R.
, and Ridgway
, S. H.
(2004
). “Structural and functional imaging of bottlenose dolphin (Tursiops truncatus) cranial anatomy
,” J. Exp. Biol.
207
(21
), 3657
–3665
.19.
Jing
, X.
, Xiao
, Y.
, and Jing
, R.
(1982
). “The acoustic function of the melon of Chinese River Dolphin (Lipotes vexillifer)
,” Acta Acust.
7
(1
), 14
–22
.20.
Kloepper
, L.
, Buck
, J. R.
, Smith
, A. B.
, Supin
, A. Y.
, Gaudette
, J. E.
, and Nachtigall
, P. E.
(2015
). “Support for the beam focusing hypothesis in the false killer whale
,” J. Exp. Biol.
218
(15
), 2455
–2462
.21.
Kloepper
, L.
, Nachtigall
, P. E.
, Donahue
, M. J.
, and Breese
, M.
(2012
). “Active echolocation beam focusing in the false killer whale, Pseudorca crassidens
,” J. Exp. Biol.
215
(8
), 1306
–1312
.22.
Krysl
, P.
, Cranford
, T. W.
, Wiggins
, S. M.
, and Hildebrand
, J. A.
(2006
). “Simulating the effect of high-intensity sound on cetaceans: Modeling approach and a case study for Cuvier's beaked whale (Ziphius cavirostris)
,” J. Acoust. Soc. Am.
120
(4
), 2328
–2339
.23.
Madsen
, P. T.
, Lammers
, M.
, Winsniewaska
, D.
, and Beedholm
, K.
(2013
). “Nasal sound production in echolocating delphinids (Tursiops truncates and Pseudorca crassidens) is dynamic, but unilateral: Clicking on the right side and whistling on the left side
,” J. Exp. Biol.
216
(21
), 4091
–4102
.24.
Madsen
, P. T.
, Wisniewska
, D.
, and Beedholm
, K.
(2010
). “Single source sound production and dynamic beam formation in echolocating harbour porpoises (Phocoena phocoena)
,” J. Exp. Biol.
213
(18
), 3105
–3110
.25.
McKenna
, M. F.
(2005
). “Comparative morphology of the odontocete melon: Functional and evolutionary interpretations
,” MSc thesis, San Diego State University
, San Diego, CA
.26.
Moore
, P. W.
, Dankiewicz
, L. A.
, and Houser
, D. S.
(2008
). “Beamwidth control and angular target detection in an echolocating bottlenose dolphin (Tursiops truncatus)
,” J. Acoust. Soc. Am.
124
(5
), 3324
–3332
.27.
Norris
, K. S.
, and Harvey
, G. W.
(1974
). “Sound transmission in the porpoise head
,” J. Acoust. Soc. Am.
56
(2
), 659
–664
.28.
Norris
, K. S.
, Prescott
, J. H.
, Asa-Drian
, P. V.
, and Perkins
, P.
(1961
). “An experimental demonstration of echolocation behavior in the porpoise, Tursiops truncatus (Montagu)
,” Biol. Bull.
120
(2
), 163
–176
.29.
Soldevilla
, M. S.
, McKenna
, M. F.
, Wiggins
, S. M.
, Shadwick
, R. E.
, Cranford
, T. W.
, and Hildebrand
, J. A.
(2005
). “Cuvier's beaked whale (Ziphius cavirostris) head tissues: Physical properties and CT imaging
,” J. Exp. Biol.
208
(12
), 2319
–2332
.30.
Song
, Z.
, Zhang
, Y.
, Wei
, C.
, and Wang
, X.
(2016
). “Inducing rostrum interfacial waves by fluid-solid coupling in a Chinese river dolphin (Lipotes vexillifer)
,” Phys. Rev. E
93
, 012411
.31.
Wei
, C.
, Au
, W. W. L.
, Ketten
, R. D.
, Song
, Z.
, and Zhang
, Y.
(2017
). “Biosonar signal propagation in the harbor porpoise's (Phocoena phocoena) head: The role of various structures in the formation of the vertical beam
,” J. Acoust. Soc. Am.
141
(6
), 4179
–4187
.32.
Wei
, C.
, Au
, W. W. L.
, Song
, Z.
, and Yu
, Z.
(2016
). “The role of various structures in the head on the formation of the biosonar beam of the baiji (Lipotes vexillifer)
,” J. Acoust. Soc. Am.
139
(2
), 875
–880
.33.
Wei
, C.
, Song
, Z.
, Au
, W. W. L.
, Zhang
, Y.
, and Wang
, D.
(2018
). “A numerical evidence of biosonar beam forming of a neonate Yangtze finless porpoise (Neophocaena asiaeorientalis)
,” J. Comput. Acoust.
26
, 1850009
.34.
Wei
, C.
, Wang
, Z.
, Song
, Z.
, Wang
, K.
, Wang
, D.
, Au
, W. W. L.
, and Yu
, Z.
(2015
). “Acoustic property reconstruction of a neonate Yangtze finless porpoise's (Neophocaena asiaeorientalis) head based on CT Imaging
,” PLoS One
10
(4
), e0121442
.35.
Wei
, C.
, Yu
, Z.
, and Au
, W. W. L.
(2014
). “Simulation of ultrasound beam formation of baiji (Lipotes vexillifer) with a finite element model
,” J. Acoust. Soc. Am.
136
(1
), 423
–429
.36.
Zhang
, Y.
, Song
, Z.
, Wang
, X.
, Cao
, W.
, and Au
, W. W. L.
(2017
). “Directional acoustic wave manipulation by a porpoise via multiphase forehead structure
,” Phys. Rev. Appl.
8
, 064002
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