386
W.W.L.Au
100
Z
0
H
80
~
u
~
c 60
~
{rl
a:
a: 40
0
u
~
20 -6
-4
-2
0
2
4
6
8
E/R (dB)
FIGURE 9.15. Bottlenose dolphin and beluga whale target detection performance as
a function of the echo-to-reverberation ratio for dR = 0 (targets were in the plane
of the clutter screen). The E/R based on a 264-J.ls integration time are indicated by
closed symbols and those based on peak-to-peak values are indicated by open
symbols. The solid lines are linear curved fitted to the data. (Modified from data
presented by Turl et aI., 1991.)
Ee/R e of 2.3 dB and Epp/Rpp of 2.5 dB. The value of EJR e of 2.3 dB is in good
agreement with an Ee/R e of 4dB determined by Au (1992) for the bottom
reverberation situation with T. truncatus. The 50% correct detection threshold for the beluga whale corresponded to Ee/R e of -2.7 dB and EpplRpp of
-0.6 dB. It is extremely interesting that the target echo can be smaller on
both a peak-to-peak and energy basis than the clutter screen echo, and yet
the beluga was able to detect the target. The results also indicated that the
beluga was approximately 3.2 to 5.0dB more sensitive than the bottlenose
dolphin in detecting a target in reverberation.
Perhaps one of the most amazing echolocation target detection and discrimination behaviors exhibited by dolphins is the "crater feeding" behavior of T. truncatus in the waters of the Grand Bahama Island (Herzing 1996;
Rossbach and Herzing 1997). These dolphins have been observed foraging
for prey buried under the sand by positioning about 3 m above the bottom
and rotating their heads alternately in a clockwise and counterclockwise
motion while performing echolocation scanning, or by swimming about
1 m above the bottom and scanning in a side-to-side motion with their
bodies parallel to the bottom. A photograph of a bottlenose dolphin burrowing into the sandy sediment to capture its prey and the crater impressions from several such burrowings can be found in Rossbach and Herzing
(1997). The buried prey is probably being detected by echolocation since
W.W.L.Au
100
Z
0
H
80
~
u
~
c 60
~
{rl
a:
a: 40
0
u
~
20 -6
-4
-2
0
2
4
6
8
E/R (dB)
FIGURE 9.15. Bottlenose dolphin and beluga whale target detection performance as
a function of the echo-to-reverberation ratio for dR = 0 (targets were in the plane
of the clutter screen). The E/R based on a 264-J.ls integration time are indicated by
closed symbols and those based on peak-to-peak values are indicated by open
symbols. The solid lines are linear curved fitted to the data. (Modified from data
presented by Turl et aI., 1991.)
Ee/R e of 2.3 dB and Epp/Rpp of 2.5 dB. The value of EJR e of 2.3 dB is in good
agreement with an Ee/R e of 4dB determined by Au (1992) for the bottom
reverberation situation with T. truncatus. The 50% correct detection threshold for the beluga whale corresponded to Ee/R e of -2.7 dB and EpplRpp of
-0.6 dB. It is extremely interesting that the target echo can be smaller on
both a peak-to-peak and energy basis than the clutter screen echo, and yet
the beluga was able to detect the target. The results also indicated that the
beluga was approximately 3.2 to 5.0dB more sensitive than the bottlenose
dolphin in detecting a target in reverberation.
Perhaps one of the most amazing echolocation target detection and discrimination behaviors exhibited by dolphins is the "crater feeding" behavior of T. truncatus in the waters of the Grand Bahama Island (Herzing 1996;
Rossbach and Herzing 1997). These dolphins have been observed foraging
for prey buried under the sand by positioning about 3 m above the bottom
and rotating their heads alternately in a clockwise and counterclockwise
motion while performing echolocation scanning, or by swimming about
1 m above the bottom and scanning in a side-to-side motion with their
bodies parallel to the bottom. A photograph of a bottlenose dolphin burrowing into the sandy sediment to capture its prey and the crater impressions from several such burrowings can be found in Rossbach and Herzing
(1997). The buried prey is probably being detected by echolocation since