Echolocation signals emitted by odontocetes can be roughly classified into three broad categories: broadband echolocation signals, narrowband high-frequency echolocation signals, and frequency modulated clicks. Previous measurements of broadband echolocation signal propagation in the bottlenose dolphin (Tursiops truncatus) did not find any evidence of focusing as the signals travel from the near-field to far-field. Finite element analysis (FEA) of high-resolution computed tomography scan data was used to examine signal propagation of broadband echolocation signals of dolphins and narrowband echolocation signals of porpoises. The FEA results were used to simulate the propagation of clicks from phonic lips, traveling through the forehead, and finally transmission into the water. Biosonar beam formation in the near-field and far-field, including the amplitude contours for the two species, was determined. The finite element model result for the simulated amplitude contour in the horizontal plane was consistent with prior direct measurement results for Tursiops, validating the model. Furthermore, the simulated far-field transmission beam patterns in both the vertical and horizontal planes were also qualitatively consistent with results measured from live animals. This study indicates that there is no evidence of convergence for either Tursiops or Phocoena as the sound propagates from the near-field to the far-field.
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Integr Zool
December 2024
College of Biological and Pharmaceutical, China Three Gorges University, Yichang, Hubei Province, China.
The genus Typhlomys comprises six species that all exhibit exceptional climbing agility in arboreal habitats, of which five have been established to use ultrasonic echolocation in the 80-120-kHz frequency range to navigate among tree branches. Here, we investigated the ultrasonic vocalizations of the remaining and recently recognized species, T. fengjiensis, and compared its ultrasonic and morphological traits with its sibling species T.
View Article and Find Full Text PDFJ Acoust Soc Am
December 2024
Cooperative Institute for Marine Ecosystem and Resources Studies and Marine Mammal Institute, Oregon State University and National Oceanic and Atmospheric Administration Pacific Marine Environmental Laboratory, Newport, Oregon 97365, USA.
Confidence intervals of location of calling marine mammals, derived from time differences of arrival (TDOA) between receivers, depend on errors of TDOAs, receiver location, clocks, sound speeds, and location method. Simulations demonstrate Ishmael, a TDOA locator based on uncorrected least squares minimization (ULSM), yields errors with mean, standard deviation, and maximum of 0.1, 0.
View Article and Find Full Text PDFSTAR Protoc
December 2024
Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe 610-0394, Japan. Electronic address:
Because bats emit ultrasound and listen to echoes to perceive their surroundings, presenting phantom echoes is useful for understanding their perception of echolocation. Here, we present a protocol for the real-time playback of phantom echoes, especially from approaching objects. We describe steps for presenting virtual objects using a microphone, digital signal processor, and loudspeaker to induce the escape behavior of bats.
View Article and Find Full Text PDFCurr Biol
December 2024
Department of Psychological and Brain Sciences, Johns Hopkins University, Baltimore, MD 21218, USA; Kavli Neuroscience Discovery Institute, Johns Hopkins University, Baltimore, MD 21218, USA; The Solomon Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA.
Echolocating bats rely on rapid processing of auditory information to guide moment-to-moment decisions related to echolocation call design and flight path selection. The fidelity of sonar echoes, however, can be disrupted in natural settings due to occlusions, noise, and conspecific jamming signals. Behavioral sensorimotor adaptation to external blocks of relevant cues has been studied extensively, but little is known about adaptations that mitigate internal sensory flow interruption.
View Article and Find Full Text PDFProc Biol Sci
November 2024
The Solomon H. Snyder Dept of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Hearing mediates many behaviours critical for survival in echolocating bats, including foraging and navigation. Although most mammals are susceptible to progressive age-related hearing loss, the evolution of biosonar, which requires the ability to hear low-intensity echoes from outgoing sonar signals, may have selected against the development of hearing deficits in bats. Many echolocating bats exhibit exceptional longevity and rely on acoustic behaviours for survival to old age; however, relatively little is known about the ageing bat auditory system.
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