. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. TARGET REPRESENTATION IN BATS steadily declining echo delay to squeeze in more sounds for more rapid updates of the sonar images (Griffin, 1958; Hartley, 1992;Novick, 1977; Schnitzler and Hen- son, 1980; see model of interception by Kuc, 1994). Perception of Targets Echo delay and target range Each broadcast sound illuminates, or ensonifics, the target for only a few milliseconds, followed by a silent interval during which echoes are received (Fig. 2). Dur- ing the interval following each broadcast, echoes return from object
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. TARGET REPRESENTATION IN BATS steadily declining echo delay to squeeze in more sounds for more rapid updates of the sonar images (Griffin, 1958; Hartley, 1992;Novick, 1977; Schnitzler and Hen- son, 1980; see model of interception by Kuc, 1994). Perception of Targets Echo delay and target range Each broadcast sound illuminates, or ensonifics, the target for only a few milliseconds, followed by a silent interval during which echoes are received (Fig. 2). Dur- ing the interval following each broadcast, echoes return from objects at different distances according to the ve- locity of sound until echoes become so weak that they can no longer be detected (Griffin. 1958; Lawrence and Simmons, 1982). In air, the delay of echoes is ms per meter of target range. Because Eptesiciis has a max- imum effective operating range of about 5 m for its so- nar system, the bat can be expected to experience delays up to about 30 ms (Kick and Simmons. 1984) and rou- tinely must cope with delays from less than 1 ms to 15- 20ms during its nightly activities (Griffin, 1958). In Figure 2, the first echo has a delay of about 10 ms. Suc- cessive echoes decrease in delay as the bat flies nearer to the target until delays become as short as ms just prior to the moment of capture when the insect is only about 5-10 cm from the bat's mouth. The bat reg- ulates the duration of its broadcasts using knowledge of echo delay from one broadcast to the next; at the mo- ment of capture the bat positions its tail membrane to seize the insect (Schnitzler and Henson, 1980; Sim- mons, 1989). The bat perceives the target's direction and distance from the echo received after each broadcast and updates the images from one broadcast to the next to follow the target's changing position. When the insect flies near branches and leaves (several kinds of night-flying insects take such evasive action upon hearing the attacking bat—see Fent
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
