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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

Call adjustments for frequency streaming in Eptesicus fuscus. Upper left photo illustrating bats vocalizing in close proximity. Photo taken by Jessica Nelson, and image assembled by Chen Chiu. Upper right plots adjustment in call frequency as a function of baseline call separation across bat pairs. Bats with similar baseline calls made larger adjustments in the end frequency the FM sweep of their calls than those with different baseline calls. Bottom panel shows raw sonar signal recording segment from two bats flying together in close proximity. Call assignment to the vocalizing bat could be made by combining three microphone recordings and 3D video position data. Adapted from Chiu et al. (2009).
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Figure 5: Call adjustments for frequency streaming in Eptesicus fuscus. Upper left photo illustrating bats vocalizing in close proximity. Photo taken by Jessica Nelson, and image assembled by Chen Chiu. Upper right plots adjustment in call frequency as a function of baseline call separation across bat pairs. Bats with similar baseline calls made larger adjustments in the end frequency the FM sweep of their calls than those with different baseline calls. Bottom panel shows raw sonar signal recording segment from two bats flying together in close proximity. Call assignment to the vocalizing bat could be made by combining three microphone recordings and 3D video position data. Adapted from Chiu et al. (2009).

Mentions: A recent laboratory study investigated strategies used by echolocating animals to reduce interference from conspecifics by placing pairs of big brown bats in a situation where they competed for a single prey item (Chiu et al., 2009). This laboratory study used high-speed 3-D video and microphone array recordings that permitted unambiguous assignment of calls to the individual vocalizing bat. The results showed that the big brown bat made adjustments in the spectral characteristics of its calls when it flew with conspecifics, and the magnitude of these adjustments depended on the baseline similarity of calls produced by the individual bats when flying alone (Figure 5). Bats that produced sonar calls with similar baseline signal design made larger adjustments in their sonar calls than those bats whose baseline call designs were already dissimilar. Field recordings from the same species showed frequency adjustments of up to 8 kHz, when two individuals flew closely together (Surlykke and Moss, 2000). Bates et al. (2008) demonstrated that frequency adjustments of paired big brown bats can aid in target detection. It is noteworthy that free-tailed bats, Tadarida brasiliensis, can prevent mutual interference by avoiding emission of sounds at the same time (Jarvis et al., 2010). Also, Gillam et al. (2007) reported that free-tailed bats changed emitted call frequency in response to signal playbacks in the field by 3–4 kHz, corroborating Habersetzer's (1981) suggestion that the frequency shifts in Rhinopoma hardwickei were jamming avoidance responses (see Table 1). These findings imply that frequency features of sonar calls produced by different bats aid each individual in segregating echoes of its own sonar vocalizations from the acoustic signals of neighboring bats (Chiu et al., 2009). Distinct frequency components of an individual's calls could be used by the bat to hear out the signals of interest (echoes from its own calls) from background (calls and echoes from other bats).


Probing the natural scene by echolocation in bats.

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

Call adjustments for frequency streaming in Eptesicus fuscus. Upper left photo illustrating bats vocalizing in close proximity. Photo taken by Jessica Nelson, and image assembled by Chen Chiu. Upper right plots adjustment in call frequency as a function of baseline call separation across bat pairs. Bats with similar baseline calls made larger adjustments in the end frequency the FM sweep of their calls than those with different baseline calls. Bottom panel shows raw sonar signal recording segment from two bats flying together in close proximity. Call assignment to the vocalizing bat could be made by combining three microphone recordings and 3D video position data. Adapted from Chiu et al. (2009).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 5: Call adjustments for frequency streaming in Eptesicus fuscus. Upper left photo illustrating bats vocalizing in close proximity. Photo taken by Jessica Nelson, and image assembled by Chen Chiu. Upper right plots adjustment in call frequency as a function of baseline call separation across bat pairs. Bats with similar baseline calls made larger adjustments in the end frequency the FM sweep of their calls than those with different baseline calls. Bottom panel shows raw sonar signal recording segment from two bats flying together in close proximity. Call assignment to the vocalizing bat could be made by combining three microphone recordings and 3D video position data. Adapted from Chiu et al. (2009).
Mentions: A recent laboratory study investigated strategies used by echolocating animals to reduce interference from conspecifics by placing pairs of big brown bats in a situation where they competed for a single prey item (Chiu et al., 2009). This laboratory study used high-speed 3-D video and microphone array recordings that permitted unambiguous assignment of calls to the individual vocalizing bat. The results showed that the big brown bat made adjustments in the spectral characteristics of its calls when it flew with conspecifics, and the magnitude of these adjustments depended on the baseline similarity of calls produced by the individual bats when flying alone (Figure 5). Bats that produced sonar calls with similar baseline signal design made larger adjustments in their sonar calls than those bats whose baseline call designs were already dissimilar. Field recordings from the same species showed frequency adjustments of up to 8 kHz, when two individuals flew closely together (Surlykke and Moss, 2000). Bates et al. (2008) demonstrated that frequency adjustments of paired big brown bats can aid in target detection. It is noteworthy that free-tailed bats, Tadarida brasiliensis, can prevent mutual interference by avoiding emission of sounds at the same time (Jarvis et al., 2010). Also, Gillam et al. (2007) reported that free-tailed bats changed emitted call frequency in response to signal playbacks in the field by 3–4 kHz, corroborating Habersetzer's (1981) suggestion that the frequency shifts in Rhinopoma hardwickei were jamming avoidance responses (see Table 1). These findings imply that frequency features of sonar calls produced by different bats aid each individual in segregating echoes of its own sonar vocalizations from the acoustic signals of neighboring bats (Chiu et al., 2009). Distinct frequency components of an individual's calls could be used by the bat to hear out the signals of interest (echoes from its own calls) from background (calls and echoes from other bats).

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