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Marlee Breese - One of the best experts on this subject based on the ideXlab platform.
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active Echolocation beam focusing in the false killer whale pseudorca crassidens
The Journal of Experimental Biology, 2012Co-Authors: Laura N Kloepper, Megan J Donahue, Paul E Nachtigall, Marlee BreeseAbstract:SUMMARY The odontocete sound production system is highly complex and produces intense, directional signals that are thought to be focused by the melon and the air sacs. Because odontocete Echolocation signals are variable and the emitted click frequency greatly affects the Echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. In this study we tested whether the Echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the Echolocation beam. The data indicate that the false killer whale changes its beam size according to target distance and difficulty, which may be a strategy of maximizing the energy of the target echo. We propose that the animal is using a strategy of changing the focal region according to target distance and that this strategy is under active control.
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Echolocation beam shape and focusing in the false killer whale pseudorca crassidens
Journal of the Acoustical Society of America, 2012Co-Authors: Laura N Kloepper, Paul E Nachtigall, Marlee BreeseAbstract:Odontocete Echolocation signals are thought to be focused by the melon and air sacs, although active focusing has yet to be demonstrated empirically. Because odontocete Echolocation signals are variable and the emitted click frequency greatly affects the Echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. Using a fine scale hydrophone array, we measured the shape of the Echolocation beam and tested whether the Echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the Echolocation beam. The false killer whale produced a single-lobed Echolocation beam that changed in size depending on target distance and difficulty which may be a strategy of actively controlling the emitted beam to maximize energy of the target echo.
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dolphin hearing during Echolocation evoked potential responses in an atlantic bottlenose dolphin tursiops truncatus
The Journal of Experimental Biology, 2011Co-Authors: Paul E Nachtigall, Marlee BreeseAbstract:Auditory evoked potential (AEP) responses were recorded during Echolocation in an Atlantic bottlenose dolphin (Tursiops truncatus) trained to accept suction-cup EEG electrodes and detect targets by Echolocation. AEP recording was triggered by the Echolocation clicks of the animal. Three targets with target strengths of -34, -28 and -22 dB were used at a target distance of 2 to 6.5 m for each target. The results demonstrated that the AEP appeared to both outgoing Echolocation clicks and echoes during Echolocation, with AEP complexes consisting of alternative positive and negative waves. The echo-related AEP amplitudes were obviously lower than the outgoing click-related AEP amplitudes for all the targets at the investigated target distances. However, for targets with target strengths of -22 and -28 dB, the peak-to-peak amplitudes of the echo-related AEPs were dependent on the target distances. The echo-related AEP response amplitudes increased at further target distances, demonstrating an overcompensation of echo attenuation with target distance in the echo-perception system of the dolphin biosonar. Measurement and analysis of outgoing click intensities showed that the click levels increased with target distance (R) by a factor of approximately 10 to 17.5 logR depending on target strength. The results demonstrated that a dual-component biosonar control system formed by intensity compensation behavior in both the transmission and receiving phases of a biosonar cycle exists synchronously in the dolphin biosonar system.
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change in Echolocation signals with hearing loss in a false killer whale pseudorca crassidens
Journal of the Acoustical Society of America, 2010Co-Authors: Laura N Kloepper, Paul E Nachtigall, Marlee BreeseAbstract:The Echolocation signals of a false killer whale (Pseudorca crassidens) were collected during a wall thickness discrimination task and compared to clicks recorded during an identical experiment in 1992. During the sixteen year time period, the subject demonstrated a loss of high frequency hearing of about 70 kHz. Clicks between the two experiments were compared to investigate the effect of hearing loss on Echolocation signals. There was a significant reduction in the peak frequency, center frequency and source level of clicks between the two time periods. Additionally, the subject currently produces more signals with low frequency peaks and fewer signals with high frequency peaks than she did in 1992. These results indicate the subject changed its Echolocation signals to match its range of best hearing.
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consistency of frequency dependent Echolocation beam focus in an echolocating false killer whale pseudorca crassidens performing a discrimination task
Journal of the Acoustical Society of America, 2008Co-Authors: Laura N Kloepper, Stuart Ibsen, Paul E Nachtigall, Marlee BreeseAbstract:Tremendous variation in individual Echolocation click parameters has been shown for odontocetes, making trend analysis of individual clicks within a click train necessary to understand their generalized Echolocation behavior. The frequency dependent spatial Echolocation beam profile of clicks for a single false killer whale (Pseudorca crassidens) performing a discrimination task was collected using a star shaped 16 hydrophone array. These spatial profiles were analyzed to compare the relative spatial location and focusing of various frequencies from click to click under different target exposures. Using a go/no go paradigm, the whale actively discriminated between objects of varying transmission reflectance properties. Very tight focusing and consistent spatial location was observed for frequencies near peak frequency but deteriorated for frequencies above peak frequency. This trend did not vary between targets, suggesting that the animal maintained a constant beam focus pattern regardless of the reflecti...
Elisabeth K V Kalko - One of the best experts on this subject based on the ideXlab platform.
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Measurement of Echolocation call parameters.
2014Co-Authors: Kirsten Jung, Jesús Molinari, Elisabeth K V KalkoAbstract:Spectrogram of Promops centralis (oscillogram, spectrogram, and power spectrum), with upward and downward modulated Echolocation calls in search phase, illustrating measurement points of Echolocation call parameters used in the analyses.
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Echolocation intensity and directionality of perching and flying fringe lipped bats trachops cirrhosus phyllostomidae
Frontiers in Physiology, 2013Co-Authors: Annemarie Surlykke, Lasse Hjort Jakobsen, Elisabeth K V Kalko, Rachel A PageAbstract:The Neotropical frog-eating bat, Trachops cirrhosus, primarily hunts stationary prey, either by gleaning on the wing, or in a sit-and-wait mode hanging from a perch. It listens passively for prey-generated sounds, but uses Echolocation in all stages of the hunt. Like other bats in the family Phyllostomidae, T.cirrhosus has a conspicuous nose leaf, hypothesized to direct and focus Echolocation calls emitted from the nostrils. T. cirrhosus is highly flexible in its cognitive abilities and its use of sensory strategies for prey detection. Additionally, T. cirrhosus has been observed to echolocate both with closed and open mouth. We hypothesize that its flexibility extends to Echolocation call design. We investigated the effect of hunting mode, perching or flying, as well as the effect of mouth opening, on the acoustic parameters and directionality of the Echolocation call. We used a multi-microphone array, a high-speed video camera, and a microphone-diode-video system to directly visualize the Echolocation sound beam synchronized with the bat’s behavior. We found that T. cirrhosus emits a highly directional sound beam with HAM (half amplitude angle) of 12o-18o and DI (directionality index) of ~17 dB, among the most directional bat sonar beams measured to date. The directionality was high both when flying and when perching. The emitted intensity was low, around 88 dB SPL at10 cm from the mouth, when hanging, but higher, around 100 dB SPL at10 cm, when flying or just before take-off. Our data suggests that the limited search volume of T.cirrhosus’ sonar beam, defined by the high directionality and the rather low intensity of its Echolocation calls, is adapted to the highly cluttered hunting habitat and to the perch hunting mode.
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perception of silent and motionless prey on vegetation by Echolocation in the gleaning bat micronycteris microtis
Proceedings of The Royal Society B: Biological Sciences, 2013Co-Authors: Inga Geipel, Elisabeth K V Kalko, Kirsten JungAbstract:Gleaning insectivorous bats that forage by using Echolocation within dense forest vegetation face the sensorial challenge of acoustic masking effects. Active perception of silent and motionless prey in acoustically cluttered environments by Echolocation alone has thus been regarded impossible. The gleaning insectivorous bat Micronycteris microtis however, forages in dense understory vegetation and preys on insects, including dragonflies, which rest silent and motionless on vegetation. From behavioural experiments, we show that M. microtis uses Echolocation as the sole sensorial modality for successful prey perception within a complex acoustic environment. All individuals performed a stereotypical three-dimensional hovering flight in front of prey items, while continuously emitting short, multi-harmonic, broadband Echolocation calls. We observed a high precision in target localization which suggests that M. microtis perceives a detailed acoustic image of the prey based on shape, surface structure and material. Our experiments provide, to our knowledge, the first evidence that a gleaning bat uses Echolocation alone for successful detection, classification and precise localization of silent and motionless prey in acoustic clutter. Overall, we conclude that the three-dimensional hovering flight of M. microtis in combination with a frequent emission of short, high-frequency Echolocation calls is the key for active prey perception in acoustically highly cluttered environments.
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bat Echolocation calls facilitate social communication
Proceedings of The Royal Society B: Biological Sciences, 2012Co-Authors: Mirjam Knornschild, Elisabeth K V Kalko, Kirsten Jung, Martina Nagy, Markus MetzAbstract:Bat Echolocation is primarily used for orientation and foraging but also holds great potential for social communication. The communicative function of Echolocation calls is still largely unstudied, especially in the wild. Eavesdropping on vocal signatures encoding social information in Echolocation calls has not, to our knowledge, been studied in free-living bats so far. We analysed Echolocation calls of the polygynous bat Saccopteryx bilineata and found pronounced vocal signatures encoding sex and individual identity. We showed experimentally that free-living males discriminate approaching male and female conspecifics solely based on their Echolocation calls. Males always produced aggressive vocalizations when hearing male Echolocation calls and courtship vocalizations when hearing female Echolocation calls; hence, they responded with complex social vocalizations in the appropriate social context. Our study demonstrates that social information encoded in bat Echolocation calls plays a crucial and hitherto underestimated role for eavesdropping conspecifics and thus facilitates social communication in a highly mobile nocturnal mammal.
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Echolocation call intensity and directionality in flying short-tailed fruit bats, Carollia perspicillata (Phyllostomidae).
The Journal of the Acoustical Society of America, 2011Co-Authors: Signe Brinkløv, Elisabeth K V Kalko, John M Ratcliffe, Lasse Hjort Jakobsen, Annemarie SurlykkeAbstract:The directionality of bat Echolocation calls defines the width of bats’ sonar “view,” while call intensity directly influences detection range since adequate sound energy must impinge upon objects to return audible echoes. Both are thus crucial parameters for understanding biosonar signal design. Phyllostomid bats have been classified as low intensity or “whispering bats,” but recent data indicate that this designation may be inaccurate. Echolocation beam directionality in phyllostomids has only been measured through electrode brain-stimulation of restrained bats, presumably excluding active beam control via the noseleaf. Here, a 12-microphone array was used to measure Echolocation call intensity and beam directionality in the frugivorous phyllostomid, Carollia perspicillata, echolocating in flight. The results showed a considerably narrower beam shape (half-amplitude beam angles of approximately 16° horizontally and 14° vertically) and louder Echolocation calls [source levels averaging 99 dB sound pressu...
Paul E Nachtigall - One of the best experts on this subject based on the ideXlab platform.
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active Echolocation beam focusing in the false killer whale pseudorca crassidens
The Journal of Experimental Biology, 2012Co-Authors: Laura N Kloepper, Megan J Donahue, Paul E Nachtigall, Marlee BreeseAbstract:SUMMARY The odontocete sound production system is highly complex and produces intense, directional signals that are thought to be focused by the melon and the air sacs. Because odontocete Echolocation signals are variable and the emitted click frequency greatly affects the Echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. In this study we tested whether the Echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the Echolocation beam. The data indicate that the false killer whale changes its beam size according to target distance and difficulty, which may be a strategy of maximizing the energy of the target echo. We propose that the animal is using a strategy of changing the focal region according to target distance and that this strategy is under active control.
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Echolocation beam shape and focusing in the false killer whale pseudorca crassidens
Journal of the Acoustical Society of America, 2012Co-Authors: Laura N Kloepper, Paul E Nachtigall, Marlee BreeseAbstract:Odontocete Echolocation signals are thought to be focused by the melon and air sacs, although active focusing has yet to be demonstrated empirically. Because odontocete Echolocation signals are variable and the emitted click frequency greatly affects the Echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. Using a fine scale hydrophone array, we measured the shape of the Echolocation beam and tested whether the Echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the Echolocation beam. The false killer whale produced a single-lobed Echolocation beam that changed in size depending on target distance and difficulty which may be a strategy of actively controlling the emitted beam to maximize energy of the target echo.
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single lobed frequency dependent beam shape in an echolocating false killer whale pseudorca crassidens
Journal of the Acoustical Society of America, 2012Co-Authors: Laura N Kloepper, Paul E Nachtigall, Christopher Quintos, Stephanie VlachosAbstract:Recent studies indicate some odontocetes may produce Echolocation beams with a dual-lobed vertical structure. The shape of the odontocete Echolocation beam was further investigated in a false killer whale performing an Echolocation discrimination task. Clicks were recorded with an array of 16 hydrophones and frequency-dependent amplitude plots were constructed to assess beam shape. The majority of the Echolocation clicks were single-lobed in structure with most energy located between 20 and 80 kHz. These data indicate the false killer whale does not produce a dual-lobed structure, as has been shown in bottlenose dolphins, which may be a function of lowered frequencies in the emitted signal due to hearing loss.
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dolphin hearing during Echolocation evoked potential responses in an atlantic bottlenose dolphin tursiops truncatus
The Journal of Experimental Biology, 2011Co-Authors: Paul E Nachtigall, Marlee BreeseAbstract:Auditory evoked potential (AEP) responses were recorded during Echolocation in an Atlantic bottlenose dolphin (Tursiops truncatus) trained to accept suction-cup EEG electrodes and detect targets by Echolocation. AEP recording was triggered by the Echolocation clicks of the animal. Three targets with target strengths of -34, -28 and -22 dB were used at a target distance of 2 to 6.5 m for each target. The results demonstrated that the AEP appeared to both outgoing Echolocation clicks and echoes during Echolocation, with AEP complexes consisting of alternative positive and negative waves. The echo-related AEP amplitudes were obviously lower than the outgoing click-related AEP amplitudes for all the targets at the investigated target distances. However, for targets with target strengths of -22 and -28 dB, the peak-to-peak amplitudes of the echo-related AEPs were dependent on the target distances. The echo-related AEP response amplitudes increased at further target distances, demonstrating an overcompensation of echo attenuation with target distance in the echo-perception system of the dolphin biosonar. Measurement and analysis of outgoing click intensities showed that the click levels increased with target distance (R) by a factor of approximately 10 to 17.5 logR depending on target strength. The results demonstrated that a dual-component biosonar control system formed by intensity compensation behavior in both the transmission and receiving phases of a biosonar cycle exists synchronously in the dolphin biosonar system.
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change in Echolocation signals with hearing loss in a false killer whale pseudorca crassidens
Journal of the Acoustical Society of America, 2010Co-Authors: Laura N Kloepper, Paul E Nachtigall, Marlee BreeseAbstract:The Echolocation signals of a false killer whale (Pseudorca crassidens) were collected during a wall thickness discrimination task and compared to clicks recorded during an identical experiment in 1992. During the sixteen year time period, the subject demonstrated a loss of high frequency hearing of about 70 kHz. Clicks between the two experiments were compared to investigate the effect of hearing loss on Echolocation signals. There was a significant reduction in the peak frequency, center frequency and source level of clicks between the two time periods. Additionally, the subject currently produces more signals with low frequency peaks and fewer signals with high frequency peaks than she did in 1992. These results indicate the subject changed its Echolocation signals to match its range of best hearing.
Jiang Feng - One of the best experts on this subject based on the ideXlab platform.
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size and quality information in acoustic signals of rhinolophus ferrumequinum in distress situations
Physiology & Behavior, 2017Co-Authors: Tinglei Jiang, Xiaobin Huang, Jiang FengAbstract:Many animals produce alarm or distress calls when they encounter predators. Previous studies have shown that the distress calls of some birds can also signal the quality of the bird as prey to predators. In this case, both predator and prey may benefit from sharing information about prey's ability to escape. However, little is known about whether Echolocation pulses and distress calls in bats convey size and quality information in distress situations. This study investigates the relationship between Echolocation, distress calls, and the health of the callers to determine whether these signals are reliable indicators of sender's attributes and quality. The spectro-temporal structure of Echolocation pulses and distress calls from captured greater horseshoe bats, Rhinolophus ferrumequinum, were found to be correlated to their body size, body condition, and T-cell-mediated immunocompetence. The peak frequency of Echolocation pulses was found to be positively correlated with the bats' forearm length. However, regression analysis has shown that no significant relationship exists between distress calls and overall body size, or between distress calls and overall health. These results suggest that the peak frequency of Echolocation pulses may be a reliable index signal to attract conspecifics, but distress calls of bats may not convey information about their size or overall quality as conspecifics or prey. These results indicate that distress calls in bats may only convey their emotional state, to attract conspecifics and facilitate estimation of predation risk.
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Patterns and causes of geographic variation in bat Echolocation pulses.
Integrative zoology, 2015Co-Authors: Tinglei Jiang, Jiang FengAbstract:Evolutionary biologists have a long-standing interest in how acoustic signals in animals vary geographically, because divergent ecology and sensory perception play an important role in speciation. Geographic comparisons are valuable in determining the factors that influence divergence of acoustic signals. Bats are social mammals and they depend mainly on Echolocation pulses to locate prey, to navigate and to communicate. Mounting evidence shows that geographic variation of bat Echolocation pulses is common, with a mean 5-10 kHz differences in peak frequency, and a high level of individual variation may be nested in this geographical variation. However, understanding the geographic variation of Echolocation pulses in bats is very difficult, because of differences in sample and statistical analysis techniques as well as the variety of factors shaping the vocal geographic evolution. Geographic differences in Echolocation pulses of bats generally lack latitudinal, longitudinal and elevational patterns, and little is known about vocal dialects. Evidence is accumulating to support the fact that geographic variation in Echolocation pulses of bats may be caused by genetic drift, cultural drift, ecological selection, sexual selection and social selection. Future studies could relate geographic differences in Echolocation pulses to social adaptation, vocal learning strategies and patterns of dispersal. In addition, new statistical techniques and acoustic playback experiments may help to illustrate the causes and consequences of the geographic evolution of Echolocation pulse in bats.
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geographical variation in Echolocation vocalizations of the himalayan leaf nosed bat contribution of morphological variation and cultural drift
Oikos, 2015Co-Authors: Aiqing Lin, Tinglei Jiang, Jinhong Luo, Jagmeet S Kanwal, Xuewen Wei, Bo Luo, Jiang FengAbstract:Ecologists and evolutionary biologists have a long-standing interest in the patterns and causes of geographical variation in animals’ acoustic signals. Nonetheless, the processes driving acoustic divergence are still poorly understood. Here, we studied the geographical variation in Echolocation vocalizations (commonly referred to as Echolocation ‘pulses’ given their short duration and relatively stereotypic nature, and to contrast them from the communicative vocalizations or ‘calls’) of a widespread bat species Hipposideros armiger in south China, and assessed whether the acoustic divergence was driven by either ecological selection, or cultural or genetic drift. Our results revealed that the peak frequency of Echolocation pulses varied significantly across populations sampled, with the maximum variation of about 6 kHz. The peak frequency clustered into three groups: eastern and western China, Hainan and southern Yunnan. The population differences in Echolocation pulses were not significantly related to the variation in climatic (mean annual temperature, mean annual relative humidity, and mean annual precipitable water) or genetic (genetic distance) factors, but significantly related to morphological (forearm length) variation which was correlated with mean annual temperature. Moreover, the acoustic differences were significantly correlated with geographical and latitudinal distance after controlling for ‘morphological distance’. Thus, neither direct ecological selection nor genetic drift contributed to the acoustic divergence observed in H. armiger. Instead, we propose that the action of both indirect ecological selection (i.e. selection on body size) as well as cultural drift promote, in part, divergence in Echolocation vocalizations of individuals within geographically distributed populations.
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different auditory feedback control for Echolocation and communication in horseshoe bats
PLOS ONE, 2013Co-Authors: Jiang Feng, Ying Liu, Walter MetznerAbstract:Auditory feedback from the animal's own voice is essential during bat Echolocation: to optimize signal detection, bats continuously adjust various call parameters in response to changing echo signals. Auditory feedback seems also necessary for controlling many bat communication calls, although it remains unclear how auditory feedback control differs in Echolocation and communication. We tackled this question by analyzing Echolocation and communication in greater horseshoe bats, whose Echolocation pulses are dominated by a constant frequency component that matches the frequency range they hear best. To maintain echoes within this “auditory fovea”, horseshoe bats constantly adjust their Echolocation call frequency depending on the frequency of the returning echo signal. This Doppler-shift compensation (DSC) behavior represents one of the most precise forms of sensory-motor feedback known. We examined the variability of Echolocation pulses emitted at rest (resting frequencies, RFs) and one type of communication signal which resembles an Echolocation pulse but is much shorter (short constant frequency communication calls, SCFs) and produced only during social interactions. We found that while RFs varied from day to day, corroborating earlier studies in other constant frequency bats, SCF-frequencies remained unchanged. In addition, RFs overlapped for some bats whereas SCF-frequencies were always distinctly different. This indicates that auditory feedback during Echolocation changed with varying RFs but remained constant or may have been absent during emission of SCF calls for communication. This fundamentally different feedback mechanism for Echolocation and communication may have enabled these bats to use SCF calls for individual recognition whereas they adjusted RF calls to accommodate the daily shifts of their auditory fovea.
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plasticity in Echolocation calls of myotis macrodactylus chiroptera vespertilionidae implications for acoustic identification
Acta Theriologica, 2012Co-Authors: Jinhong Luo, Ying Liu, Jing Wang, Lei Wang, Jiang FengAbstract:Poor knowledge of the intraspecific variability in Echolocation calls is recognized as an important limiting factor for the accurate acoustic identification of bats. We studied the Echolocation behaviors of an ecologically poorly known bat species, Myotis macrodactylus, while they were commuting in three types of habitats differing significantly in the amount of background clutter, as well as searching for prey above the water surface in a river. Results showed that M. macrodactylus altered their Echolocation call structure in the same way during commuting as foraging bats do in relation to the changing level of clutter. With increasing level of clutter, M. macrodactylus generally produced Echolocation calls with higher start, end, and peak frequencies; wider bandwidth; and shorter pulse duration. Compared to commuting, bats emitted significantly lower frequency calls with narrower bandwidth while searching for prey. Discriminant function analysis indicated that 79.8% of the calls from the three commuting habitats were correctly grouped, and 87% of the calls were correctly classified to the commuting and foraging contexts. Our finding has implications for those who would identify species by their calls.
Laura N Kloepper - One of the best experts on this subject based on the ideXlab platform.
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active Echolocation beam focusing in the false killer whale pseudorca crassidens
The Journal of Experimental Biology, 2012Co-Authors: Laura N Kloepper, Megan J Donahue, Paul E Nachtigall, Marlee BreeseAbstract:SUMMARY The odontocete sound production system is highly complex and produces intense, directional signals that are thought to be focused by the melon and the air sacs. Because odontocete Echolocation signals are variable and the emitted click frequency greatly affects the Echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. In this study we tested whether the Echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the Echolocation beam. The data indicate that the false killer whale changes its beam size according to target distance and difficulty, which may be a strategy of maximizing the energy of the target echo. We propose that the animal is using a strategy of changing the focal region according to target distance and that this strategy is under active control.
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Echolocation beam shape and focusing in the false killer whale pseudorca crassidens
Journal of the Acoustical Society of America, 2012Co-Authors: Laura N Kloepper, Paul E Nachtigall, Marlee BreeseAbstract:Odontocete Echolocation signals are thought to be focused by the melon and air sacs, although active focusing has yet to be demonstrated empirically. Because odontocete Echolocation signals are variable and the emitted click frequency greatly affects the Echolocation beam shape, investigations of beam focusing must account for frequency-related beam changes. Using a fine scale hydrophone array, we measured the shape of the Echolocation beam and tested whether the Echolocation beam of a false killer whale changed depending on target difficulty and distance while also accounting for frequency-related changes in the Echolocation beam. The false killer whale produced a single-lobed Echolocation beam that changed in size depending on target distance and difficulty which may be a strategy of actively controlling the emitted beam to maximize energy of the target echo.
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single lobed frequency dependent beam shape in an echolocating false killer whale pseudorca crassidens
Journal of the Acoustical Society of America, 2012Co-Authors: Laura N Kloepper, Paul E Nachtigall, Christopher Quintos, Stephanie VlachosAbstract:Recent studies indicate some odontocetes may produce Echolocation beams with a dual-lobed vertical structure. The shape of the odontocete Echolocation beam was further investigated in a false killer whale performing an Echolocation discrimination task. Clicks were recorded with an array of 16 hydrophones and frequency-dependent amplitude plots were constructed to assess beam shape. The majority of the Echolocation clicks were single-lobed in structure with most energy located between 20 and 80 kHz. These data indicate the false killer whale does not produce a dual-lobed structure, as has been shown in bottlenose dolphins, which may be a function of lowered frequencies in the emitted signal due to hearing loss.
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change in Echolocation signals with hearing loss in a false killer whale pseudorca crassidens
Journal of the Acoustical Society of America, 2010Co-Authors: Laura N Kloepper, Paul E Nachtigall, Marlee BreeseAbstract:The Echolocation signals of a false killer whale (Pseudorca crassidens) were collected during a wall thickness discrimination task and compared to clicks recorded during an identical experiment in 1992. During the sixteen year time period, the subject demonstrated a loss of high frequency hearing of about 70 kHz. Clicks between the two experiments were compared to investigate the effect of hearing loss on Echolocation signals. There was a significant reduction in the peak frequency, center frequency and source level of clicks between the two time periods. Additionally, the subject currently produces more signals with low frequency peaks and fewer signals with high frequency peaks than she did in 1992. These results indicate the subject changed its Echolocation signals to match its range of best hearing.
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consistency of frequency dependent Echolocation beam focus in an echolocating false killer whale pseudorca crassidens performing a discrimination task
Journal of the Acoustical Society of America, 2008Co-Authors: Laura N Kloepper, Stuart Ibsen, Paul E Nachtigall, Marlee BreeseAbstract:Tremendous variation in individual Echolocation click parameters has been shown for odontocetes, making trend analysis of individual clicks within a click train necessary to understand their generalized Echolocation behavior. The frequency dependent spatial Echolocation beam profile of clicks for a single false killer whale (Pseudorca crassidens) performing a discrimination task was collected using a star shaped 16 hydrophone array. These spatial profiles were analyzed to compare the relative spatial location and focusing of various frequencies from click to click under different target exposures. Using a go/no go paradigm, the whale actively discriminated between objects of varying transmission reflectance properties. Very tight focusing and consistent spatial location was observed for frequencies near peak frequency but deteriorated for frequencies above peak frequency. This trend did not vary between targets, suggesting that the animal maintained a constant beam focus pattern regardless of the reflecti...
