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Strasbourg, France

Sivle L.D.,Norwegian Institute of Marine Research | Kvadsheim P.H.,Norwegian Defence Research Establishment FFI | Cure C.,Acoustics Group | Isojunno S.,University of St. Andrews | And 8 more authors.
Aquatic Mammals

Controlled exposure experiments using 1 to 2 kHz sonar signals were conducted with 11 humpback whales (Megaptera novaeangliae), one minke whale (Balaenoptera acutorostrata), and one northern bottlenose whale (Hyperoodon ampullatus) during three field trials from 2011 to 2013. Ship approaches without sonar transmis-sions, playbacks of killer whale vocalizations, and broadband noise were conducted as controls. Behavioural parameters such as horizontal move-ment, diving, social interactions, and vocalizations were recorded by animal-attached tags and by visual and acoustic tracking. Based on these data, two expert panels independently scored the sever-ity of behavioural changes that were judged likely to be responses to the experimental stimuli, using a severity scale ranging from no effect (0) to high potential to affect vital rates (9) if exposed repeat-edly. After scoring, consensus was reached with a third-party moderator. In humpback whales, killer whale playbacks induced more severe responses than sonar exposure, and both sonar expo-sures and killer whale playbacks induced more responses and responses of higher severity than the no-sonar ship approaches and broadband noise playbacks. The most common response during sonar exposures in all three species was avoidance of the sound source. The most severe responses to sonar (severity 8) were progressive high-speed avoidance by the minke whale and long-term area avoidance by the bottlenose whale. Other severe responses included prolonged avoidance and ces-sation of feeding (severity 7). The minke whale and bottlenose whale started avoiding the source at a received sound pressure level (SPL) of 146 and 130 dB re 1 μPa, respectively. Humpback whales generally had less severe responses that were triggered at higher received levels. The probability of severity scores with the potential to affect vital rates increased with increasing sound exposure level (SELcum). The single experiments with minke and bottlenose whales suggest they cumhave greater susceptibility to sonar disturbance than humpback whales, but additional studies are needed to confirm this result. Source

Cure C.,Acoustics Group | Cure C.,CNRS Neuroscience Paris-Saclay Institute | Cure C.,University Paris - Sud | Mathevon N.,CNRS Neuroscience Paris-Saclay Institute | And 2 more authors.
Behavioural Processes

Vocal recognition is an important process allowing partners' reunion in most seabirds. Although the acoustic basis of this recognition has been explored in several species, only a few studies have experimentally tested the acoustic coding-decoding strategy used for mate identification. Here, we investigated mate recognition in the Scopoli's shearwater (Calonectris diomedea) by conducting playbacks of calls with modified acoustic features. We showed that females and males in a seabird species with a moderate vocal dimorphism are likely to share the same coding-decoding rule for vocal mate identification. Specifically, a disruption of call temporal strsucture prevented mate recognition in both sexes, in line with the parameters previously identified as supporting an individual signature. Modifications of spectral cues and envelope structure also impaired recognition, but at a lesser extent: almost half of the tested males and females were still able to recognise their partner. It is likely that this equal ability of female and male Scopoli's shearwaters to vocally recognise their partner could be found in other seabirds. © 2016 Elsevier B.V. Source

Colin Y.,Airbus | Colin Y.,Numerical Acoustics Group | Blanc F.,Airbus | Blanc F.,Numerical Method Aerodynamic Group | And 6 more authors.
18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

This paper is the second part of a series of three papers dedicated to the prediction of low-speed interaction noise of an isolated Contra-Rotating Open Rotor (CROR). The objective is to investigate the URANS chorochronic approach for computing the unsteady flow across both rotors. The stress is to be put on the correct description and propagation of the wake deficit, which is essential for capturing the unsteady loading onto the rear row and thus the resulting interaction noise. Chorochronic methods are attractive because they require the computation of a single channel only and thus are less costly than full-annulus CFD computations (such as sliding mesh or Chimera techniques). Therefore, the chorochronic technique is used in this study to investigate various mesh topologies. It is shown that the method presents very good agreement with experimental data in absolute levels at a very reasonable cost. © 2012 by The Authors and AIRBUS S.A.S. Source

Colin Y.,Airbus | Colin Y.,Numerical Acoustics Group | Carazo A.,Airbus | Carazo A.,Acoustics Group | And 5 more authors.
18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference)

This paper is the first part of a series of three papers dedicated to the prediction of low-speed interaction noise of an isolated contra-rotating open rotor (CROR). The objective of this study is to assess available analytical and numerical methodologies in terms of robustness, performance and accuracy. The analytical procedure follows the classical Sears' theory, while the numerical procedure follows a two-step approach based on CFD coupled with the analogy of Ffowcs Williams-Hawkings (FWH). Concerning the numerical tools, both chorochronic (single-passage) and Chimera (full-annulus) approaches are considered. The prediction of interaction noise requires fulfilling three modelling steps: the aerodynamic perturbations, the rotor unsteady blade response and the resulting noise radiation. Comparisons with noise measurements are provided. It is shown that the results are highly sensitive to the description of the incoming wake deficit. The chorochronic approach, as a single blade passage is computed, allows the use of much finer meshes than the Chimera approach and requires a lower computational cost. This approach is therefore highly attractive for computing isolated axisymmetric configurations. © 2012 by The Authors, AIRBUS S.A.S and Rolls-Royce. Source

Isojunno S.,University of St. Andrews | Cure C.,Acoustics Group | Kvadsheim P.H.,Norwegian Defence Research Establishment FFI | Lam F.-P.A.,Applied Scientific Research | And 3 more authors.
Ecological Applications

The time and energetic costs of behavioral responses to incidental and experimental sonar exposures, as well as control stimuli, were quantifi ed using hidden state analysis of time series of acoustic and movement data recorded by tags (DTAG) attached to 12 sperm whales (Physeter macrocephalus) using suction cups. Behavioral state transition modeling showed that tagged whales switched to a non-foraging, non-resting state during both experimental transmissions of low-frequency active sonar from an approaching vessel (LFAS; 1-2 kH z, source level 214 dB re 1 μ Pa m, four tag records) and playbacks of potential predator (killer whale, Orcinus orca) sounds broadcast at naturally occurring sound levels as a positive control from a drifting boat (fi ve tag records). Time spent in foraging states and the probability of prey capture attempts were reduced during these two types of exposures with little change in overall locomotion activity, suggesting an effect on energy intake with no immediate compensation. Whales switched to the active non-foraging state over received sound pressure levels of 131-165 dB re 1 μ Pa during LFAS exposure. In contrast, no changes in foraging behavior were detected in response to experimental negative controls (no-sonar ship approach or noise control playback) or to experimental medium-frequency active sonar exposures (MFAS; 6-7 kH z, source level 199 re 1 μ Pa m, received sound pressure level [SPL] = 73-158 dB re 1 μ Pa). Similarly, there was no reduction in foraging effort for three whales exposed to incidental, unidenti-fi ed 4.7-5.1 kH z sonar signals received at lower levels (SPL = 89-133 dB re 1 μ Pa). These results demonstrate that similar to predation risk, exposure to sonar can affect functional behaviors, and indicate that increased perception of risk with higher source level or lower frequency may modulate how sperm whales respond to anthropogenic sound. © 2016 by the Ecological Society of America. Source

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