Global ETD Search
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Showing 1 to 20 of 74 for “"echolocation"”.
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Bat Skull Evolution: the Impact of Echolocation
… to other drivers of adaptation (in particular echolocation) remains understudied. In this thesis, I investigated the relationship between bat skull morphology (i.e., size and shape) and functional traits (i.e., feeding and echolocation) with a focus on the echolocation adaptations. I applied …
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Echolocation in wild killer whales (Orcinus orca)
Echolocation by odontocete whales has been demonstrated in captive settings many times, yet little is known about its use and function in the wild. In this thesis, I describe echolocation sounds in pods of killer whales (Orcinus orca) off the coasts of British Columbia and Alaska. I examine the …
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A psychophysical study of echolocation in the blinded rat
LD2668 .T4 1966 B435
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Development and application of an echolocation model inspired by bats
This study explores the principles of echolocation in bats which can be potentially<br/>adopted for bio-inspired sonar systems. Using a biological signal processing technique<br/>which was developed based on bat’s hearing system, the effect of auditory processing<br/>on the object discrimination is …
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The function of modified echolocation pulses in horseshoe bats (Family: Rhinolophidae)
Recent studies suggest that echolocation pulses may be implicated in communication. In one of these studies, the horseshoe bat, Rhinolophus clivosus, was found to emit echolocation pulses with an unusual and pronounced upsweep at the end of the echolocation pulse (at the FM component). It was …
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Echolocation: Using Word-Burst Analysis to Rescore Keyword Search Candidates in Low-Resource Languages
<p>State of the art technologies for speech recognition are very accurate for heavily studied languages like English. They perform poorly, though, for languages wherein the recorded archives of speech data available to researchers are relatively scant. In the context of these low-resource …
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Molecular phylogenetics and the evolution of high-frequency echolocation in horseshoe bats (Genus Rhinolophus)
… are high-duty cycle bats and many species use echolocation calls dominated by high frequencies (above 60 kHz). Much is known about how they use their echolocation calls, but very little is known about why these bats use echolocation calls of such high frequencies, or what has caused the …
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Effects of Echolocation Calls on the Interactions of Bat Pairs using Transfer Entropy Analysis
… in that they use the active sensing mechanism of echolocation as their primary means of navigation. Due to their use of echolocation in large groups, bats run the risk of signal interference from sonar jamming. However, several species of bats have developed various strategies to prevent …
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Acoustic scattering of broadband echolocation signals from prey of Blainville's beaked whales : modeling and analysis
… densirostris) use broadband, ultrasonic echolocation signals (27 to 57 kHz) to search for, localize, and approach prey that generally consist of mid-water and deep-water fishes and squid. Although it is well known that the spectral characteristics of broadband echoes from marine organisms …
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Acoustic scattering of broadband echolocation signals from prey of Blainville's beaked whales : modeling and analysis
… densirostris) use broadband, ultrasonic echolocation signals (27 to 57 kHz) to search for, localize, and approach prey that generally consist of mid-water and deep-water fishes and squid. Although it is well known that the spectral characteristics of broadband echoes from marine organisms …
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Echolocation-based foraging by harbor porpoises and sperm whales, including effects of noise and acoustic propagation
… quantitative descriptions of toothed whale echolocation and foraging behavior, including assessment of the effects of noise on foraging behavior and the potential influence of ocean acoustic propagation conditions on biosonar detection ranges and whale noise exposure. In addition to …
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Geographic variation in the echolocation calls of the endemic Cape horseshoe bat, Rhinolophus capensis (Chiroptera: Rhinolophidae)
… study has investigated geographic variation in echolocation calls of R. capensis. Body size, wing morphology and skull parameters associated with diet and echolocation call production and reception, were compared between populations. Adult R. capensis were sampled at three sites: De Hoop …
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Echolocation-based foraging by harbor porpoises and sperm whales, including effects of noise and acoustic propagation
… quantitative descriptions of toothed whale echolocation and foraging behavior, including assessment of the effects of noise on foraging behavior and the potential influence of ocean acoustic propagation conditions on biosonar detection ranges and whale noise exposure. In addition to …
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The role of echolocation in communication in a high duty cycle echolocating bat, Rhinolophus clivosus (Chiroptera: Rhinolophidae): an experimental approach
… parameters (e.g. frequency). Horseshoe bats use echolocation for the purpose of orientation and foraging. However, given the presence of individual and species specific cues in echolocation, it is likely that echolocation also functions to some degree in acoustic communication. This dual function …
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Geographic variation in the phenotypes of two sibling horseshoe bats Rhinolophus simulator and R.swinnyi
… southern Africa and several morphometric and echolocation parameters were taken. The relative contributions of adaptation and drift were first tested (Chapter 2) using the Lande's model. It was hypothesised that adaptation would predominate in the diversification of the two horseshoe bats …
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Variation of echolocation pulse source levels and detection distances for bat assemblages across an environmental gradient: “a test of the acoustic adaptation hypothesis”
The use of multiple microphone arrays to measure echolocation pulse source levels of free-flying bats does not allow one to determine the species of the bat being recorded. However, the echolocation pulses can be assigned to species based on pulse parameters used in conjunction with a reference …
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The influence of foraging habitat on acoustic signal source levels in two bat species, Neoromicia capensis (Vespertilionidae) and Tadarida aegyptiaca (Molossidae)
The source level of echolocation pulses is an essential parameter because it has an impact on the range at which bats perceive their environment and, most importantly, at which they detect prey. Echolocation pulse source level is under the control of the echolocator and its operational range is …
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Classification and Processing of Communication Calls in Little Brown Bats, Myotis Lucifugus
… included -- downward FM (DFM), courtship, and echolocation. Reversed DFM and silence groups were used as a comparison for basal activity. Call-dependent egr1 expression was found in all subdivisions of the thalamus and IC. Specifically, the central nucleus of the IC showed robust expression for …
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Behavioural evidence for the perception of individual identity and gender via the echolocation calls of a high duty cycle bat, Rhinolophus clivosus
… to a highly specialized form of sonar called echolocation. In habituation-dishabituation experiments, a high duty cycle echolocating bat, Rhinolophus clivosus, dishabituated significantly when echolocation calls of a different gender or individual were played to the habituation. Strong …
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Target strength of bat prey in relation to pulse frequency and vegetation density in bat species, Rhinolophus fumigatus (Rüppell's horseshoe bat)
The relationship between echolocation and morphology is evident in several insectivorous bat species where a negative correlation between peak echolocation frequency and body size is observed. However, there are various exceptions to the general allometric relationship observed between body size …
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