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Paul E Nachtigall - One of the best experts on this subject based on the ideXlab platform.
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cognitive adaptation of sonar gain control in the Bottlenose Dolphin
PLOS ONE, 2014Co-Authors: Laura N Kloepper, Paul E Nachtigall, Adam B Smith, John R Buck, James A Simmons, Aude F PaciniAbstract:Echolocating animals adjust the transmit intensity and receive sensitivity of their sonar in order to regulate the sensation level of their echoes; this process is often termed automatic gain control. Gain control is considered not to be under the animal's cognitive control, but previous investigations studied animals ensonifying targets or hydrophone arrays at predictable distances. To test whether animals maintain gain control at a fixed level in uncertain conditions, we measured changes in signal intensity for a Bottlenose Dolphin (Tursiops truncatus) detecting a target at three target distances (2.5, 4 and 7 m) in two types of sessions: predictable and unpredictable. Predictable sessions presented the target at a constant distance; unpredictable sessions moved the target randomly between the three target positions. In the predictable sessions the Dolphin demonstrated intensity distance compensation, increasing the emitted click intensity as the target distance increased. Additionally, as trials within sessions progressed, the animal adjusted its click intensity even from the first click in a click train, which is consistent with the animal expecting a target at a certain range. In the unpredictable sessions there was no significant difference of intensity with target distance until after the 7th click in a click train. Together, these results demonstrate that the Bottlenose Dolphin uses learning and expectation for sonar gain control.
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conditioned hearing sensitivity reduction in a Bottlenose Dolphin tursiops truncatus
The Journal of Experimental Biology, 2014Co-Authors: Paul E Nachtigall, Alexander Ya. SupinAbstract:The conditioned change in hearing sensitivity during a warning sound preceding a loud sound was investigated in the Bottlenose Dolphin. Hearing sensitivity was measured using pip-train test stimuli and auditory evoked potential recording. When the test/warning stimulus with a frequency of 22.5 or 32 kHz preceded the loud sound with a frequency of 22.5 kHz and a sound pressure level of 165 dB re. 1 μPa rms, hearing thresholds before the loud sound increased relative to the baseline. The threshold increased up to 15 dB. In order to further investigate whether the observed threshold increase was due to conditioning, the dependence of the effect on warning duration and inter-trial interval was investigated. The duration of the warning substantially influenced the effect. Shorter warnings resulted in deeper suppression of responses and higher threshold increases than longer warnings. In contrast, the effect was nearly independent of the duration of the inter-trial interval, i.e. it was independent of the delay from the loud sound to the test/warning sound in the subsequent trial. These data are considered as evidence that the observed hearing threshold increases were not a result of the unconditioned effect of the loud sound and were instead a manifestation of a conditioned dampening of hearing when the Bottlenose Dolphin anticipated the quick appearance of a loud sound in the same way as previously demonstrated in the false killer whale.
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not so automatic gain control in the Bottlenose Dolphin source level distance compensation depends on prior knowledge of target distance
Journal of the Acoustical Society of America, 2013Co-Authors: Laura N Kloepper, Paul E Nachtigall, Adam B SmithAbstract:Although termed “automatic gain control,” previous field and laboratory investigations into source level distance compensation in bats and odontocetes have relied on animals echolocating targets or arrays at predictable distances. To test the “automatic” nature of gain control in the Bottlenose Dolphin, the source level distance compensation was measured for three target distances (2, 4, and 7 m) in two types of sessions: predictable, in which the target distance was held constant within a session, and random, in which the target distance varied within a session. In the predicable sessions the Dolphin demonstrated source level distance compensation at a rate of 10 log (distance), a level approximately half that predicted by past gain control experiments. In the random sessions the Dolphin did not demonstrate source level distance compensation and, regardless of target distance, produced source levels that were equivalent to those produced for the predictable sessions at 4 m distance. These data suggest th...
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hearing sensation levels of emitted biosonar clicks in an echolocating atlantic Bottlenose Dolphin
PLOS ONE, 2012Co-Authors: Paul E Nachtigall, Marlee Breese, Alexander Ya. SupinAbstract:Emitted biosonar clicks and auditory evoked potential (AEP) responses triggered by the clicks were synchronously recorded during echolocation in an Atlantic Bottlenose Dolphin (Tursiops truncatus) trained to wear suction-cup EEG electrodes and to detect targets by echolocation. Three targets with target strengths of -34, -28, and -22 dB were used at distances of 2 to 6.5 m for each target. The AEP responses were sorted according to the corresponding emitted click source levels in 5-dB bins and averaged within each bin to extract biosonar click-related AEPs from noise. The AEP amplitudes were measured peak-to-peak and plotted as a function of click source levels for each target type, distance, and target-present or target-absent condition. Hearing sensation levels of the biosonar clicks were evaluated by comparing the functions of the biosonar click-related AEP amplitude-versus-click source level to a function of external (in free field) click-related AEP amplitude-versus-click sound pressure level. The results indicated that the Dolphin's hearing sensation levels to her own biosonar clicks were equal to that of external clicks with sound pressure levels 16 to 36 dB lower than the biosonar click source levels, varying with target type, distance, and condition. These data may be assumed to indicate that the Bottlenose Dolphin possesses effective protection mechanisms to isolate the self-produced intense biosonar beam from the animal's ears during echolocation.
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predicting temporary threshold shifts in a Bottlenose Dolphin tursiops truncatus the effects of noise level and duration
Journal of the Acoustical Society of America, 2009Co-Authors: Aran T Mooney, Paul E Nachtigall, Marlee Breese, Stephanie VlachosAbstract:Noise levels in the ocean are increasing and are expected to affect marine mammals. To examine the auditory effects of noise on odontocetes, a Bottlenose Dolphin (Tursiops truncatus) was exposed to octave-band noise (4–8kHz) of varying durations (<2–30min) and sound pressures (130–178dB re 1μPa). Temporary threshold shift (TTS) occurrence was quantified in an effort to (i) determine the sound exposure levels (SELs) (dB re 1μPa2s) that induce TTS and (ii) develop a model to predict TTS onset. Hearing thresholds were measured using auditory evoked potentials. If SEL was kept constant, significant shifts were induced by longer duration exposures but not for shorter exposures. Higher SELs were required to induce shifts in shorter duration exposures. The results did not support an equal-energy model to predict TTS onset. Rather, a logarithmic algorithm, which increased in sound energy as exposure duration decreased, was a better predictor of TTS. Recovery to baseline hearing thresholds was also logarithmic (ap...
Paul M Thompson - One of the best experts on this subject based on the ideXlab platform.
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quantifying the effect of boat disturbance on Bottlenose Dolphin foraging activity
Biological Conservation, 2015Co-Authors: Enrico Pirotta, Paul M Thompson, Nathan D Merchant, Tim R Barton, David LusseauAbstract:Assessments of anthropogenic impacts on marine wildlife often concentrate on large-scale displacement. However, changes in the activity patterns of animals that do not flee could also affect their energy balance. Increasing boat traffic raises concerns for exposed marine mammals. Understanding risk perception is critical for effective mitigation and management, but it is hard to disentangle the effect of noise, physical presence of boats, and context. We used passive acoustic techniques to quantify how boat disturbance affected Bottlenose Dolphin foraging activity, and characterized the conditions influencing responses. To account for potential masking effects of boat noise on foraging vocalizations (buzzes), we developed a novel procedure to estimate the relationship between buzz detection probability and noise levels in particular 1/3 octave bands. Bayesian hierarchical modeling was then used to assess the effect of boat presence on buzz occurrence, as well as potential interactions with noise level, location, year, day, hour, Dolphin group size, and boat type and number. Our results indicate that boat presence was associated with a short-term 49% reduction in foraging activity, but there was no relationship with noise level. Differences between sites and between years suggested a variable susceptibility depending on foraging conditions. This effect increased for increasing number of boats and depended on boat type. This is the first study conclusively showing that boat physical presence, and not just noise, plays a large role in disturbance.
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estimating size and assessing trends in a coastal Bottlenose Dolphin population
Ecological Applications, 1999Co-Authors: Ben Wilson, Philip S Hammond, Paul M ThompsonAbstract:We used a case study of a coastal Bottlenose Dolphin population to present a framework for determining the number of individuals present and assessing the likely time scale over which trends in abundance may be determined. Such a framework is appropriate for animal species that possess natural markings sufficient for individual recognition, and may be valuable in the development and implementation of management and monitoring programs for vulnerable populations. Population abundance was estimated using mark–recapture methods applied to photoidentification data. This experiment was designed to minimize violation of method assumptions so as to allow use of the most parsimonious model for analysis. The data were examined critically to investigate mark–recapture assumptions, while analytical methods and data were selected to minimize and, where necessary, account for violations. The estimated number of animals with long-lasting marks from left and right side estimates were 73 ± 12 and 80 ± 11 individuals, res...
Ben Wilson - One of the best experts on this subject based on the ideXlab platform.
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estimating size and assessing trends in a coastal Bottlenose Dolphin population
Ecological Applications, 1999Co-Authors: Ben Wilson, Philip S Hammond, Paul M ThompsonAbstract:We used a case study of a coastal Bottlenose Dolphin population to present a framework for determining the number of individuals present and assessing the likely time scale over which trends in abundance may be determined. Such a framework is appropriate for animal species that possess natural markings sufficient for individual recognition, and may be valuable in the development and implementation of management and monitoring programs for vulnerable populations. Population abundance was estimated using mark–recapture methods applied to photoidentification data. This experiment was designed to minimize violation of method assumptions so as to allow use of the most parsimonious model for analysis. The data were examined critically to investigate mark–recapture assumptions, while analytical methods and data were selected to minimize and, where necessary, account for violations. The estimated number of animals with long-lasting marks from left and right side estimates were 73 ± 12 and 80 ± 11 individuals, res...
Andre E Moura - One of the best experts on this subject based on the ideXlab platform.
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Drivers of Population Structure of the Bottlenose Dolphin (Tursiops truncatus) in the Eastern Mediterranean Sea
Evolutionary Biology, 2015Co-Authors: Stefania Gaspari, Chiara Natali, Draško Holcer, Caterina Fortuna, Guido Chelazzi, Tilen Genov, Aviad Scheinin, Alexandros Frantzis, Andre E MouraAbstract:The drivers of population differentiation in oceanic high dispersal organisms, have been crucial for research in evolutionary biology. Adaptation to different environments is commonly invoked as a driver of differentiation in the oceans, in alternative to geographic isolation. In this study, we investigate the population structure and phylogeography of the Bottlenose Dolphin (Tursiops truncatus) in the Mediterranean Sea, using microsatellite loci and the entire mtDNA control region. By further comparing the Mediterranean populations with the well described Atlantic populations, we addressed the following hypotheses: (1) Bottlenose Dolphins show population structure within the environmentally complex Eastern Mediterranean Sea; (2) population structure was gained locally or otherwise results from chance distribution of pre-existing genetic structure; (3) strong demographic variations within the Mediterranean basin have affected genetic variation sufficiently to bias detected patterns of population structure. Our results suggest that Bottlenose Dolphin exhibits population structures that correspond well to the main Mediterranean oceanographic basins. Furthermore, we found evidence for fine scale population division within the Adriatic and the Levantine seas. We further describe for the first time, a distinction between populations inhabiting pelagic and coastal regions within the Mediterranean. Phylogeographic analysis suggests that current genetic structure, results mostly from stochastic distribution of Atlantic genetic variation, during a recent post-glacial expansion. Comparison with Atlantic mtDNA haplotypes, further suggest the existence of a metapopulation across North Atlantic/Mediterranean, with pelagic regions acting as source for coastal environments.
Alexander Ya. Supin - One of the best experts on this subject based on the ideXlab platform.
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spatial release from masking in a Bottlenose Dolphin tursiops truncatus
Journal of the Acoustical Society of America, 2020Co-Authors: V V Popov, Alexander Ya. Supin, A P Gvozdeva, Dmitry I Nechaev, Mikhail B Tarakanov, Evgeniya SysuevaAbstract:The impact of maskers on the receiving beam of a Bottlenose Dolphin, Tursiops truncatus, was investigated using the auditory evoked potential (AEP) method. The test signal was a train of tone pips with a 64 kHz carrier frequency. The stimulus produced AEPs as a sequence of waves replicating the pip rate: the rate following response (RFR). The masker was band-limited noise, with a passband of 45 to 90 kHz and a level of 105 dB re 1 μPa. Masker azimuths were at 0°, ±30°, ±60°, and ±90° relative to the head midline. The receiving beam was evaluated in terms of the RFR threshold dependence on the signal azimuth. The masked thresholds were higher than the baseline thresholds, which appeared mostly as a shift rather than a deformation in the receiving beam. The largest threshold shift appeared when the masker source was located in the most sensitive direction (zero azimuth); at lateral masker source positions, the threshold shift decreased. When the masker source was not at the head midline, the masked thresholds were higher at signal positions ipsilateral to the masker source than at positions contralateral to the masker source. The largest asymmetry was observed at the 30° masker azimuth in conjunction with the ±30° and ±120° signal azimuths; the asymmetries were 5.6 and 8.1 dB, respectively. This masking asymmetry was lower than expected from the previously found interaural intensity difference, which may be explained by the conflict between the test signal and the masker when it appeared at a binaural level of the auditory system.
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discrimination of ripple spectra in a Bottlenose Dolphin in quiet and after noise exposure
Journal of the Acoustical Society of America, 2019Co-Authors: Dmitry I Nechaev, Alexander Ya. Supin, Mikhail B Tarakanov, V Popov, Evgeniya SysuevaAbstract:The frequency resolving power (FRP) of hearing in quiet and after noise exposure was measured in a Bottlenose Dolphin using rippled-spectrum test stimuli and noninvasive recording of rhythmic evoked responses (the rate following response, RFR) to ripple phase reversals. Both the test signal and noise had band-limited spectra with the same central frequency; however, the noise had a non-rippled spectrum. The noise level was from -20 to 10 dB re test signal level. The baseline ripple density resolution depended on signal level and was the highest at levels from 80 to 100 dB re 1 μPa. At signal levels both above (up to 130 dB re 1 μPa) and below (down to 80 dB re 1 μPa) the optimal level, the ripple density resolution decreased. The impact of noise was different for different test signal levels. For low test signal levels (70 to 100 dB re 1 μPa), noise decreased RFR magnitude and resolution, whereas for high test signal levels (110 to 130 dB re 1μPa), low-level noise increased RFR magnitude and resolution. [Work supported by the Russian Science Foundation (Project 17-74-20107) awarded to E.V.S.]
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conditioned hearing sensitivity reduction in a Bottlenose Dolphin tursiops truncatus
The Journal of Experimental Biology, 2014Co-Authors: Paul E Nachtigall, Alexander Ya. SupinAbstract:The conditioned change in hearing sensitivity during a warning sound preceding a loud sound was investigated in the Bottlenose Dolphin. Hearing sensitivity was measured using pip-train test stimuli and auditory evoked potential recording. When the test/warning stimulus with a frequency of 22.5 or 32 kHz preceded the loud sound with a frequency of 22.5 kHz and a sound pressure level of 165 dB re. 1 μPa rms, hearing thresholds before the loud sound increased relative to the baseline. The threshold increased up to 15 dB. In order to further investigate whether the observed threshold increase was due to conditioning, the dependence of the effect on warning duration and inter-trial interval was investigated. The duration of the warning substantially influenced the effect. Shorter warnings resulted in deeper suppression of responses and higher threshold increases than longer warnings. In contrast, the effect was nearly independent of the duration of the inter-trial interval, i.e. it was independent of the delay from the loud sound to the test/warning sound in the subsequent trial. These data are considered as evidence that the observed hearing threshold increases were not a result of the unconditioned effect of the loud sound and were instead a manifestation of a conditioned dampening of hearing when the Bottlenose Dolphin anticipated the quick appearance of a loud sound in the same way as previously demonstrated in the false killer whale.
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hearing sensation levels of emitted biosonar clicks in an echolocating atlantic Bottlenose Dolphin
PLOS ONE, 2012Co-Authors: Paul E Nachtigall, Marlee Breese, Alexander Ya. SupinAbstract:Emitted biosonar clicks and auditory evoked potential (AEP) responses triggered by the clicks were synchronously recorded during echolocation in an Atlantic Bottlenose Dolphin (Tursiops truncatus) trained to wear suction-cup EEG electrodes and to detect targets by echolocation. Three targets with target strengths of -34, -28, and -22 dB were used at distances of 2 to 6.5 m for each target. The AEP responses were sorted according to the corresponding emitted click source levels in 5-dB bins and averaged within each bin to extract biosonar click-related AEPs from noise. The AEP amplitudes were measured peak-to-peak and plotted as a function of click source levels for each target type, distance, and target-present or target-absent condition. Hearing sensation levels of the biosonar clicks were evaluated by comparing the functions of the biosonar click-related AEP amplitude-versus-click source level to a function of external (in free field) click-related AEP amplitude-versus-click sound pressure level. The results indicated that the Dolphin's hearing sensation levels to her own biosonar clicks were equal to that of external clicks with sound pressure levels 16 to 36 dB lower than the biosonar click source levels, varying with target type, distance, and condition. These data may be assumed to indicate that the Bottlenose Dolphin possesses effective protection mechanisms to isolate the self-produced intense biosonar beam from the animal's ears during echolocation.
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Comparison of directional selectivity of hearing in a beluga whale and a Bottlenose Dolphin
The Journal of the Acoustical Society of America, 2009Co-Authors: Vladimir V. Popov, Alexander Ya. SupinAbstract:Hearing thresholds as a function of sound-source azimuth were measured in a beluga whale Delphinapterus leucas and a Bottlenose Dolphin Tursiops truncatus in identical conditions using the auditory evoked-potential method. In both the beluga whale and Bottlenose Dolphin, the receiving beam width narrowed with frequency increase. At all frequencies, the receiving beam was markedly wider in the beluga whale than in the Bottlenose Dolphin. In particular, the 3-dB beam width in the beluga whale narrowed from +/-33.5 degrees at 8 kHz frequency to +/-14.3 degrees at 128 kHz; the 6-dB beam width narrowed from +/-56.9 degrees to +/-18.9 degrees , respectively. In the Bottlenose Dolphin, the 3-dB beam width decreased from +/-19.9 degrees at 8 kHz to +/-6.3 degrees at 128 kHz; the 6-dB beam width decreased from +/-33.1 degrees to +/-8.4 degrees, respectively. In the Bottlenose Dolphin, the axis of the low-frequency receiving beam deviated from the midline up to 15 degrees; in the beluga whale, this effect was not detected. The audiograms of both the beluga whale and Bottlenose Dolphin were azimuth-dependent: from an audiogram featuring the best sensitivity at intermediate frequencies at 0 degrees to that featuring monotonous threshold increase with frequency increase at 90 degrees. In the beluga whale, this dependence was less prominent than in the Bottlenose Dolphin.