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9:50
3aABa9. Planning for a pilot census of marine life in the Gulf of
Maine: The role of acoustics. Kenneth G. Foote 共Woods Hole
Oceanogr. Inst., Woods Hole, MA 02543, kfoote@whoi.edu兲
Preparations are being made for a pilot census of marine life in the
Gulf of Maine ecosystem. The role of acoustics as a rapid, remote sensing
tool is elaborated. Potential target organisms for acoustic surveying range
from mesozooplankton and macrozooplankton to fish and cetaceans. A
number of methodological problems must be addressed. These are illus-
trated for the echo integration method as applied to a stock of Atlantic
herring 共Clupea harengus兲关J. Acoust. Soc. Am. 105, 995 共1999兲兴. Particu-
lar problems of determining target strength and compensating for possible
behavioral effects are also general to the method. 关Work supported by the
Alfred P. Sloan Foundation.兴
10:05
3aABa10. Localizing marine animals and how marine animals might
localize sound. Gerald L. D’Spain and Paul A. Lepper 共Marine Physical
Lab., Scripps Inst. of Oceanogr., La Jolla, CA 92093-0704兲
We can locate vocalizing marine animals, and the animals themselves
might locate sound sources, in one of several ways. Time-of-arrival
共phase兲 differences and amplitude differences of a single arrival between
spatially separated ‘‘ears’’ are well-known techniques. However, they be-
come ineffective in multipath environments and as the frequency of the
sound and/or spatial separation between ears decreases. Another approach
is to sense properties of the acoustic field in addition to acoustic pressure.
This approach, based on a simple Taylor series expansion of the field and
‘‘f⫽ ma,’’ apparently is exploited by fish, making them biological equiva-
lents of DIFAR sonobuoys. However, do they also measure acoustic strain
rate? An additional method, used by humans, is to take advantage of
time-of-arrival 共phase兲 differences between multipath arrivals. The infor-
mation on source location contained in the resulting interference patterns
can be understood in terms of waveguide invariants. These speculations
will be illustrated with numerical simulations and actual ocean acousic
data. 关Work supported by ONR.兴
10:20
3aABa11. Acoustic identification of female Steller sea lions. Gregory
S. Campbell 共Cetacean Behavior Lab., San Diego State Univ., San Diego,
CA 92182-4611兲, Robert Gisner 共Code 342, Office of Naval Res.,
Arlington, VA 22217兲, and David A. Helweg 共Code D351,
SPAWARSYSCEN San Diego, San Diego, CA 92152兲
Steller sea lions 共Eumetopias jubatus兲 breed and rear their young in
coastal rookeries dispersed along the northern tier of the North Pacific.
Population densities are high and no allomaternal behavior occurs, provid-
ing strong selection pressure for mother–pup recognition processes. Moth-
ers and pups establish and maintain contact with individually distinctive
vocalizations. Our objective is to understand the acoustic features that
serve to identify individual females, and develop a ruggedized computer
system to perform acoustic recognition of females in the field. We have
cataloged almost 2000 contact calls from 46 females in 1998 and 25 in
1999. Each female is visually identified by marking patterns, which pro-
vides the ground truth for acoustic identification. Acoustic properties of
the calls were measured and presented to several statistical classifiers.
Representations of the calls had to be robust with respect to acoustical
variability introduced by motivational changes as the mother and pup re-
gained proximity. The calls, classifiers, and results of generalization tests
will be described, and a concept for the field system will be discussed.
关Research supported by ONR Research Opportunities for Program Offic-
ers award N00014-00-1-0114 to R. H. DeFran, Cetacean Behavior Labo-
ratory, SDSU.兴
WEDNESDAY MORNING, 6 DECEMBER 2000 SCHOONER/SLOOP ROOMS, 10:50 TO 11:55 A.M.
Session 3aABb
Animal Bioacoustics: General Topics in Bioacoustics
Lawrence F. Wolski, Chair
Hubbs-Sea World Research Institute, 2595 Ingraham Street, San Diego, California 92109
Chair’s Introduction—10:50
Contributed Papers
10:55
3aABb1. Infrasonic and low-frequency vocalizations from Siberian
and Bengal tigers. Elizabeth von Muggenthaler 共Fauna
Communications Res. Inst.兲
Tigers have many vocalizations including chuffling, growling, prusten,
gurgling, grunting, and roaring. It has been well documented that the
tiger’s high-amplitude, low-frequency roars, which are thought to be ter-
ritorial in nature 关C. Packer and A. E. Pusey, Sci. Am. 276, 52–59 共1997兲兴
transmit for miles. It has been suggested that because some tigers inhabit
dense jungles with limited visiblity, the capacity to hear low frequency
may be beneficial for sensing and locating prey 关G. T. Huang, J. J.
Rosowski, and W. T. Peake, J. Comp. Physiol. A 共2000兲兴. In an effort to
understand more about these low-frequency vocalizations and to provide
data to other researchers testing hearing in anesthetized felids, 22 tigers,
both Siberian and Bengal, are being recorded. A portable system can
record from 3 Hz to 22 kHz. On-site real-time analysis of vocalizations is
performed using a portable computer. Real-time and edited playback of
sonic and infrasonic tiger vocalizations is facilitated by car audio speakers
capable of producing frequencies from 10 Hz–22 kHz. Initial findings
have documented fundamental frequencies of some roars at 17.50 Hz.
Other vocalizations, including chuffling, have fundamental frequencies of
35 Hz ⫾ 5. Playback of both real-time and edited vocalizations appear to
illicit behavioral responses, such as roaring, from male tigers.
11:10
3aABb2. On the sound of snapping shrimp: The collapse of a
cavitation bubble. Michel Versluis, Anna von der Heydt,
a兲
Detlef Lohse
共Dept. of Appl. Phys. and J. M. Burgers Res. Ctr. for Fluid Dynam., Univ.
of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands兲,and
Barbara Schmitz 共TU Munchen, 85747 Garching, Germany兲
Snapping shrimp produce a snapping sound by an extremely rapid
closure of their snapper claw. They usually occur in large numbers pro-
viding a permanent crackling background noise, thereby severely limiting
the use of underwater acoustics for active and passive sonar, both in sci-
entific and naval applications. Source levels reported for Alpheus hetero-
3a WED. AM
2541 2541J. Acoust. Soc. Am., Vol. 108, No. 5, Pt. 2, November 2000 Joint 140th Meeting ASA/NOISE-CON 2000
chaelis are as high as 220 dB 共peak-to-peak兲 re 1
Pa at 1 m distance.
Recent ultra-high-speed imaging of the snapper claw closure 关Versluis
et al., Science 共in press兲兴 revealed that the sound is generated by the
collapse of a cavitation bubble formed in a fast flowing jet of water forced
out from between the claws during claw closure. In this work, we develop
a theoretical model for a bubble under such conditions. The dynamics of
the bubble radius and the emitted sound can be described by the
Rayleigh–Plesset equation. The calculated results are compared with the
experimental data. The model fully reproduces the bubble dynamics and it
quantitatively accounts for the time dependence of the bubble radius and
for the emitted sound.
a兲
Also at Dept. of Physics, Philipps-Univ. Marburg,
Renthof 6, 35032 Marburg, Germany.
11:25
3aABb3. A unique way of sound production in the snapping shrimp
„Alpheus heterochaelis…. Barbara Schmitz 共Dept. of Zoology, TU
Muenchen, Lichtenbergstr. 4, 85747 Garching, Germany兲, Michel
Versluis, Anna von der Heydt, and Detlef Lohse 共Appl. Phys., Univ. of
Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands兲
Sound production is known in more than 50, mostly stridulating, crus-
tacean genera. These acoustic signals occur in agonistic interactions as
well as for mate attraction. The mechanism of sound production in snap-
ping shrimp, which also serves to stun or even kill small prey, is especially
interesting. The current assumption was that the sound is produced by
cocking and then rapidly closing the enlarged modified snapper claw.
Snapping shrimp sounds contribute most to coastal biological noise, may
be heard up to 1 mile away, and resemble the crackling of dry twigs in fire
or the sizzle of frying fat. Recent hydrophone measurements close to
tethered shrimp 共Alpheus heterochaelis兲 revealed pulse-like signals of
500-ns duration, comprising frequencies beyond 200 kHz, and showing
enormous sound pressure levels of up to 220-dB re 1
Pa 共peak to
peak兲 at 1-m distance. Such high intensities are very unlikely to be pro-
duced by the mechanical contact of two claw surfaces. Ultra-high-speed
video recordings and simultaneous hydrophone measurements reveal that
claw closure results in a water jet, the high velocity of which 共25 m/s兲
leads to the formation of a cavitation bubble, which emits the extremely
loud sound upon its collapse.
11:40
3aABb4. Lack of species-specific vocal recognition in Amazonian
manatees: Trichechus inunguis. Renata S. Sousa Lima and Vera M. F.
da Silva 共Laborato
´
rio de Mamı
´
feros Aqua
´
ticos, INPA, C.P. 478, Manaus,
AM, Brasil 69083-000, pboi@inpa.gov.br兲
Playback experiments were conducted in order to test for the existence
of species-specific vocal recognition in Amazonian manatees. The animals
were isolated in pools while acoustic stimuli were played from a tape
recorder and transmitted underwater through a loudspeaker. Nine animals
were monitored for response to playback vocalizations from eighteen dif-
ferent individuals, nine from each species 共Trichechus inunguis and T.
manatus manatus兲. No significant differences were detected in the re-
sponse of manatees exposed to the different stimuli. Only the time spent
close to the speaker was greater when the animals were exposed to con-
specific vocalizations (
⫽ 0.375). This result suggests that Amazonian
manatees cannot recognize differences between their own and another
manatee species’ vocalization. The methodology was also tested and no
difference in the response of animals exposed to silence or to tape hiss
共blank tape used as control兲 was found. Testing the response to the pres-
ence or absence of vocalizations, significant differences were found in
time elapsed between the playback and the response (
⬍ 0.001) and in the
time spent next to the speaker (
⫽ 0.032), confirming their great ability to
perceive sounds underwater. 关Work supported by FBPN, MacArthur
Foundation, CI, FINEP, MCT/PPG7 and CNPq.兴
WEDNESDAY MORNING, 6 DECEMBER 2000 CALIFORNIA SALON 3, 7:20 A.M. TO 12:05 P.M.
Session 3aAO
Acoustical Oceanography: Special Topics
Thomas K. Berger, Cochair
Scripps Institute of Oceanography, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0238
Christopher D. Jones, Cochair
Applied Physics Laboratory, University of Washington, 1013 NE 40th Street, Seattle, Washington 98105
Chair’s Introduction—7:20
Contributed Papers
7:25
3aAO1. The F factor: Ocean climatology and internal-wave acoustic
effects. Stanley M. Flatte
´
and Kimberly J. Noble 共Phys. Dept. and Inst.
of Marine Sci., Univ. of California at Santa Cruz, Santa Cruz, CA 95064兲
The strength of acoustic fluctuations due to internal waves is affected
by the temperature-salinity relation of an oceanic region. We define an
acoustic fluctuation strength parameter F as the ratio of the fractional
potential-sound-speed change to the fractional potential-density change. F
is calculated at three depth levels 共275, 550, and 850 m兲, on a one-degree
grid of latitude and longitude, using NODC/OCL’s World Ocean Atlas
1994. Representative values of F in upper waters range between 5 and 35.
Results for intermediate depths range from 5 to 60. In general, F exhibits
higher values in the Atlantic Basin than in the Indian or Pacific, and has a
maximum at 550 m. The main use of F will be the prediction of travel-
time fluctuations in acoustic propagation experiments, which will be pro-
portional to the value of F, given a universal strength of internal waves.
7:40
3aAO2. Imaging acoustic fluctuations in shallow water using
dislocation theory. D. P. Williams, G. L. D’Spain, W. S. Hodgkiss, and
W. A. Kuperman 共Marine Physical Lab., Scripps Inst. of Oceanogr.,
Univ. of California at San Diego, La Jolla, CA 92093-0238兲
The distribution of the amplitude of a moderate-frequency sound field
in a shallow ocean is considered in relation to the existence of dislocations
in the phase front 关Nye and Berry 共1974兲兴 where the amplitude is close to
zero. Phase front dislocations strictly occur when the amplitude is zero; in
actual ocean acoustic measurements, only low-field amplitudes at a
minima can be distinguished due to the interference of background noise.
2542 2542J. Acoust. Soc. Am., Vol. 108, No. 5, Pt. 2, November 2000 Joint 140th Meeting ASA/NOISE-CON 2000
