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Probing the natural scene by echolocation in bats.

Moss CF, Surlykke A - Front Behav Neurosci (2010)

Bottom Line: Bats echolocating in the natural environment face the formidable task of sorting signals from multiple auditory objects, echoes from obstacles, prey, and the calls of conspecifics.This article reviews field and laboratory studies that document adaptive sonar behaviors of echolocating bats, and point to the fundamental signal parameters they use to track and sort auditory objects in a dynamic environment.We suggest that adaptive sonar behavior provides a window to bats' perception of complex auditory scenes.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology and Institute for Systems Research, Program in Neuroscience and Cognitive Science, University of Maryland College Park, MD, USA.

ABSTRACT
Bats echolocating in the natural environment face the formidable task of sorting signals from multiple auditory objects, echoes from obstacles, prey, and the calls of conspecifics. Successful orientation in a complex environment depends on auditory information processing, along with adaptive vocal-motor behaviors and flight path control, which draw upon 3-D spatial perception, attention, and memory. This article reviews field and laboratory studies that document adaptive sonar behaviors of echolocating bats, and point to the fundamental signal parameters they use to track and sort auditory objects in a dynamic environment. We suggest that adaptive sonar behavior provides a window to bats' perception of complex auditory scenes.

No MeSH data available.


Related in: MedlinePlus

Schematically illustrates a bat in an environment that contains a single prey item and trees at different distances. Below, each horizontal line in the plot corresponds to a sonar vocalization, starting from 1500 ms before capture until time zero (top to bottom on the left y-axis), when the bat intercepts the prey. The separation between the lines corresponds to sonar call intervals decreasing with decreasing distance to the prey. The resulting streams of echoes at changing delays are shown as open boxes with widths corresponding to call duration and color coding of the insect (black) and trees (red, blue, and green) in the panel above. The signal durations and intervals are based on a pursuit sequence recorded from Eptesicus fuscus in the wild. The acoustic phases of insect pursuit from search to terminal buzz phase are indicated on the right y-axis. As the bat flies closer to the trees and insect, the echo delays shorten. Each of the reflecting objects appears as a distinct ridge with a particular slope, corresponding to the rate of delay change of echoes over time. In this display, one can visually identify and track the returning echoes from the trees and insect over time.
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Figure 2: Schematically illustrates a bat in an environment that contains a single prey item and trees at different distances. Below, each horizontal line in the plot corresponds to a sonar vocalization, starting from 1500 ms before capture until time zero (top to bottom on the left y-axis), when the bat intercepts the prey. The separation between the lines corresponds to sonar call intervals decreasing with decreasing distance to the prey. The resulting streams of echoes at changing delays are shown as open boxes with widths corresponding to call duration and color coding of the insect (black) and trees (red, blue, and green) in the panel above. The signal durations and intervals are based on a pursuit sequence recorded from Eptesicus fuscus in the wild. The acoustic phases of insect pursuit from search to terminal buzz phase are indicated on the right y-axis. As the bat flies closer to the trees and insect, the echo delays shorten. Each of the reflecting objects appears as a distinct ridge with a particular slope, corresponding to the rate of delay change of echoes over time. In this display, one can visually identify and track the returning echoes from the trees and insect over time.

Mentions: Here we present in Figure 2 a schematic illustration of sonar streams constructed from coherent changes in echo delay, the bat's cue for target distance. Figure 2 (upper panel) shows a bat in an environment that contains a single prey item and trees at different distances. In this simplified scenario, the insect and trees are located in front of the bat, and the bat receives echoes from these objects at different and changing delays. Each panel represents a new slice in time, separated by a fixed interval. In each panel, the bat's position relative to the trees and insect changes, as the bat pursues its prey. Below, each horizontal line in the plot corresponds to a sonar vocalization, starting from 1500 ms before capture until time zero (from top to bottom on the left y-axis), when the bat intercepts the prey. The separation between the lines corresponds to the repetition rate of sonar vocalizations produced by the bat at different distances to the prey and obstacles. The resulting streams of echoes at changing delays are shown as open boxes with widths corresponding to sonar call duration and color coding as the insect (black) and trees (red, blue, and green) in the panel above. The signal durations and intervals are based on a pursuit sequence recorded from Eptesicus fuscus in the wild. The right y-axis shows the echolocation phases of insect pursuit from search to terminal buzz phase. As the bat flies closer to the trees and insect, the echo delays shorten. The echo amplitudes are estimated to illustrate relative differences due to changes in distances to the objects and the fact that bats reduce the output intensity as they close in on a target (Hartley and Suthers, 1989; Surlykke and Kalko, 2008). When the bat has passed an object the echo delay increases as the bat's distance from these objects increases, and the echo amplitude decreases rapidly to reflect the directionality of the sonar call with low intensity radiated in the backward direction. Each of the reflecting objects appears as a distinct ridge with a particular slope, corresponding to the rate of delay change of echoes over time. In this display, one can visually identify and track the returning echoes from the trees and insect over time.


Probing the natural scene by echolocation in bats.

Moss CF, Surlykke A - Front Behav Neurosci (2010)

Schematically illustrates a bat in an environment that contains a single prey item and trees at different distances. Below, each horizontal line in the plot corresponds to a sonar vocalization, starting from 1500 ms before capture until time zero (top to bottom on the left y-axis), when the bat intercepts the prey. The separation between the lines corresponds to sonar call intervals decreasing with decreasing distance to the prey. The resulting streams of echoes at changing delays are shown as open boxes with widths corresponding to call duration and color coding of the insect (black) and trees (red, blue, and green) in the panel above. The signal durations and intervals are based on a pursuit sequence recorded from Eptesicus fuscus in the wild. The acoustic phases of insect pursuit from search to terminal buzz phase are indicated on the right y-axis. As the bat flies closer to the trees and insect, the echo delays shorten. Each of the reflecting objects appears as a distinct ridge with a particular slope, corresponding to the rate of delay change of echoes over time. In this display, one can visually identify and track the returning echoes from the trees and insect over time.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2927269&req=5

Figure 2: Schematically illustrates a bat in an environment that contains a single prey item and trees at different distances. Below, each horizontal line in the plot corresponds to a sonar vocalization, starting from 1500 ms before capture until time zero (top to bottom on the left y-axis), when the bat intercepts the prey. The separation between the lines corresponds to sonar call intervals decreasing with decreasing distance to the prey. The resulting streams of echoes at changing delays are shown as open boxes with widths corresponding to call duration and color coding of the insect (black) and trees (red, blue, and green) in the panel above. The signal durations and intervals are based on a pursuit sequence recorded from Eptesicus fuscus in the wild. The acoustic phases of insect pursuit from search to terminal buzz phase are indicated on the right y-axis. As the bat flies closer to the trees and insect, the echo delays shorten. Each of the reflecting objects appears as a distinct ridge with a particular slope, corresponding to the rate of delay change of echoes over time. In this display, one can visually identify and track the returning echoes from the trees and insect over time.
Mentions: Here we present in Figure 2 a schematic illustration of sonar streams constructed from coherent changes in echo delay, the bat's cue for target distance. Figure 2 (upper panel) shows a bat in an environment that contains a single prey item and trees at different distances. In this simplified scenario, the insect and trees are located in front of the bat, and the bat receives echoes from these objects at different and changing delays. Each panel represents a new slice in time, separated by a fixed interval. In each panel, the bat's position relative to the trees and insect changes, as the bat pursues its prey. Below, each horizontal line in the plot corresponds to a sonar vocalization, starting from 1500 ms before capture until time zero (from top to bottom on the left y-axis), when the bat intercepts the prey. The separation between the lines corresponds to the repetition rate of sonar vocalizations produced by the bat at different distances to the prey and obstacles. The resulting streams of echoes at changing delays are shown as open boxes with widths corresponding to sonar call duration and color coding as the insect (black) and trees (red, blue, and green) in the panel above. The signal durations and intervals are based on a pursuit sequence recorded from Eptesicus fuscus in the wild. The right y-axis shows the echolocation phases of insect pursuit from search to terminal buzz phase. As the bat flies closer to the trees and insect, the echo delays shorten. The echo amplitudes are estimated to illustrate relative differences due to changes in distances to the objects and the fact that bats reduce the output intensity as they close in on a target (Hartley and Suthers, 1989; Surlykke and Kalko, 2008). When the bat has passed an object the echo delay increases as the bat's distance from these objects increases, and the echo amplitude decreases rapidly to reflect the directionality of the sonar call with low intensity radiated in the backward direction. Each of the reflecting objects appears as a distinct ridge with a particular slope, corresponding to the rate of delay change of echoes over time. In this display, one can visually identify and track the returning echoes from the trees and insect over time.

Bottom Line: Bats echolocating in the natural environment face the formidable task of sorting signals from multiple auditory objects, echoes from obstacles, prey, and the calls of conspecifics.This article reviews field and laboratory studies that document adaptive sonar behaviors of echolocating bats, and point to the fundamental signal parameters they use to track and sort auditory objects in a dynamic environment.We suggest that adaptive sonar behavior provides a window to bats' perception of complex auditory scenes.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology and Institute for Systems Research, Program in Neuroscience and Cognitive Science, University of Maryland College Park, MD, USA.

ABSTRACT
Bats echolocating in the natural environment face the formidable task of sorting signals from multiple auditory objects, echoes from obstacles, prey, and the calls of conspecifics. Successful orientation in a complex environment depends on auditory information processing, along with adaptive vocal-motor behaviors and flight path control, which draw upon 3-D spatial perception, attention, and memory. This article reviews field and laboratory studies that document adaptive sonar behaviors of echolocating bats, and point to the fundamental signal parameters they use to track and sort auditory objects in a dynamic environment. We suggest that adaptive sonar behavior provides a window to bats' perception of complex auditory scenes.

No MeSH data available.


Related in: MedlinePlus