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Ocean Noise

Martine Boccara, Yasmina Fedala, Catherine Venien Bryan, Marc Bailly-Bechet, Chris Bowler, Albert Claude Boccara
There is a huge abundance of viruses and membrane vesicles in seawater. We describe a new full-field, incoherently illuminated, shot-noise limited, common-path interferometric detection method that we couple with the analysis of Brownian motion to detect, quantify, and differentiate biotic nanoparticles. We validated the method with calibrated nanoparticles and homogeneous DNA or RNA viruses. The smallest virus size that we characterized with a suitable signal-to-noise ratio was around 30 nm in diameter. Analysis of Brownian motions revealed anisotropic trajectories for myoviruses...
September 1, 2016: Biomedical Optics Express
Nan Chen, Andrew J Majda
The Central Pacific El Niño (CP El Niño) has been frequently observed in recent decades. The phenomenon is characterized by an anomalous warm sea surface temperature (SST) confined to the central Pacific and has different teleconnections from the traditional El Niño. Here, simple models are developed and shown to capture the key mechanisms of the CP El Niño. The starting model involves coupled atmosphere-ocean processes that are deterministic, linear, and stable. Then, systematic strategies are developed for incorporating several major mechanisms of the CP El Niño into the coupled system...
October 3, 2016: Proceedings of the National Academy of Sciences of the United States of America
F Chen, G I Shapiro, K A Bennett, S N Ingram, D Thompson, C Vincent, D J F Russell, C B Embling
Shipping noise is a threat to marine wildlife. Grey seals are benthic foragers, and thus experience acoustic noise throughout the water column, which makes them a good model species for a case study of the potential impacts of shipping noise. We used ship track data from the Celtic Sea, seal track data and a coupled ocean-acoustic modelling system to assess the noise exposure of grey seals along their tracks. It was found that the animals experience step changes in sound levels up to ~20dB at a frequency of 125Hz, and ~10dB on average over 10-1000Hz when they dive through the thermocline, particularly during summer...
September 24, 2016: Marine Pollution Bulletin
Lisa McCarthy, Kirk N Olsen
Continuous increases of acoustic intensity (up-ramps) can indicate a looming (approaching) sound source in the environment, whereas continuous decreases of intensity (down-ramps) can indicate a receding sound source. From psychoacoustic experiments, an "adaptive perceptual bias" for up-ramp looming tonal stimuli has been proposed (Neuhoff, 1998). This theory postulates that (1) up-ramps are perceptually salient because of their association with looming and potentially threatening stimuli in the environment; (2) tonal stimuli are perceptually salient because of an association with single and potentially threatening biological sound sources in the environment, relative to white noise, which is more likely to arise from dispersed signals and nonthreatening/nonbiological sources (wind/ocean)...
September 8, 2016: Attention, Perception & Psychophysics
Timothy Onosahwo Iyendo
BACKGROUND: Sound in hospital space has traditionally been considered in negative terms as both intrusive and unwanted, and based mainly on sound levels. However, sound level is only one aspect of the soundscape. There is strong evidence that exploring the positive aspect of sound in a hospital context can evoke positive feelings in both patients and nurses. Music psychology studies have also shown that music intervention in health care can have a positive effect on patient's emotions and recuperating processes...
November 2016: International Journal of Nursing Studies
D R González, R L Speth, D V Gaitonde, M J Lewis
The finite-time Lyapunov exponent (FTLE) technique has shown substantial success in analyzing incompressible flows by capturing the dynamics of coherent structures. Recent applications include river and ocean flow patterns, respiratory tract dynamics, and bio-inspired propulsors. In the present work, we extend FTLE to the compressible flow regime so that coherent structures, which travel at convective speeds, can be associated with waves traveling at acoustic speeds. This is particularly helpful in the study of jet acoustics...
August 2016: Chaos
J T Fasullo, R S Nerem, B Hamlington
Global mean sea level rise estimated from satellite altimetry provides a strong constraint on climate variability and change and is expected to accelerate as the rates of both ocean warming and cryospheric mass loss increase over time. In stark contrast to this expectation however, current altimeter products show the rate of sea level rise to have decreased from the first to second decades of the altimeter era. Here, a combined analysis of altimeter data and specially designed climate model simulations shows the 1991 eruption of Mt Pinatubo to likely have masked the acceleration that would have otherwise occurred...
2016: Scientific Reports
John Gebbie, Martin Siderius
Ambient ocean noise is processed with a vertical line array to reveal coherent time-separated arrivals suggesting the presence of head wave multipath propagation. Head waves, which are critically propagating water waves created by seabed waves traveling parallel to the water-sediment interface, can propagate faster than water-only waves. Such eigenrays are much weaker than water-only eigenrays, and are often completely overshadowed by them. Surface-generated noise is different whereby it amplifies the coherence between head waves and critically propagating water-only waves, which is measured by cross-correlating critically steered beams...
July 2016: Journal of the Acoustical Society of America
Junghyun Park, Brian W Stump, Chris Hayward, Stephen J Arrowsmith, Il-Young Che, Douglas P Drob
This work quantifies the physical characteristics of infrasound signal and noise, assesses their temporal variations, and determines the degree to which these effects can be predicted by time-varying atmospheric models to estimate array and network performance. An automated detector that accounts for both correlated and uncorrelated noise is applied to infrasound data from three seismo-acoustic arrays in South Korea (BRDAR, CHNAR, and KSGAR), cooperatively operated by Korea Institute of Geoscience and Mineral Resources (KIGAM) and Southern Methodist University (SMU)...
July 2016: Journal of the Acoustical Society of America
Sean M Wiggins, Jesse M Hall, Bruce J Thayre, John A Hildebrand
The ocean soundscape of the Gulf of Mexico (GOM) has not been well-studied, although it is an important habitat for marine mammals, including sperm and beaked whales, many dolphin species, and a potentially endangered baleen whale species. The GOM is also home to high levels of hydrocarbon exploration and extraction, heavily used commercial shipping ports, and significant fishery industry activity, all of which are known contributors to oceanic noise. From 2010-2013, the soundscape of three deep and two shallow water sites in the GOM were monitored over 10 - 1000 Hz...
July 2016: Journal of the Acoustical Society of America
Wenbo Sun, Yongxiang Hu, David G MacDonnell, Carl Weimer, Rosemary R Baize
Sunlight contamination dominates the backscatter noise in space-based lidar measurements during daytime. The background scattered sunlight is highly variable and dependent upon the surface and atmospheric albedo. The scattered sunlight contribution to noise increases over land and snow surfaces where surface albedos are high and thus overwhelm lidar backscatter from optically thin atmospheric constituents like aerosols and thin clouds. In this work, we developed a novel lidar remote sensing concept that potentially can eliminate sunlight induced noise...
June 13, 2016: Optics Express
Luke J Hollmann, Robert L Stevenson
Passive underwater listening devices are often deployed to listen for narrowband signals of interest in time-varying background ocean noise. Such tonals are generated mechanically by ships, submarines, and machines, or acoustically by aquatic wildlife. Quantization of the sensor data for storage or low bit-rate transmission adds white noise which can overwhelm weak narrowband signals if the background noise is sufficiently colored. Whitening the background noise prior to quantization can reduce the detrimental effects, but the whitening process must preserve any tonals in the signal for maximum effectiveness...
June 2016: Journal of the Acoustical Society of America
Michele Thums, Scott D Whiting, Julia Reisser, Kellie L Pendoley, Charitha B Pattiaratchi, Maira Proietti, Yasha Hetzel, Rebecca Fisher, Mark G Meekan
We examined the effect of artificial light on the near shore trajectories of turtle hatchlings dispersing from natal beaches. Green turtle (Chelonia mydas) hatchlings were tagged with miniature acoustic transmitters and their movements tracked within an underwater array of 36 acoustic receivers placed in the near shore zone. A total of 40 hatchlings were tracked, 20 of which were subjected to artificial light during their transit of the array. At the same time, we measured current speed and direction, which were highly variable within and between experimental nights and treatments...
May 2016: Royal Society Open Science
Ana Širović, John A Hildebrand, Mark A McDonald
Comparisons of current and historic ocean ambient noise levels are rare, especially in the North Atlantic. Recent (2013-2014) monthly patterns in ocean ambient sound south of Bermuda were compared to those recorded at the same location in 1966. Additionally, trends in ocean traffic, in particular, Panama Canal traffic, over this time were also investigated. One year of ocean ambient noise measurements were collected in 1966 using cabled, omnidirectional hydrophones at the U.S. Navy Tudor Hill Laboratory in Bermuda, and repeat measurements were collected at the same location from June 2013-May 2014 using a High-frequency Acoustic Recording Package...
May 2016: Journal of the Acoustical Society of America
Jin-jia Guo, Yuan Lu, Chun-hao Liu, Rong-er Zheng
Spectroscopic sensor is becoming an important issue for the deep-sea exploration due to the advantages of multi-specie, multi-phases and stand-off detection. Different approach have been developing in recent years based on LIBS (Laser Induced Breakdown Spectroscopy) and Raman spectroscopy since Raman-LIBS are complementary techniques with the similar components and the capability of molecular and elementary analysis. In this work, we built a LIBS-Raman system and detected Na2SO4 in aqueous solution to evaluate the potential ocean application...
January 2016: Guang Pu Xue Yu Guang Pu Fen Xi, Guang Pu
Jonathan T Hagstrum, Hugh P McIsaac, Douglas P Drob
Repeated releases of experienced homing pigeons from single sites were conducted between 1972 and 1974 near Cornell University in upstate New York and between 1982 and 1983 near the University of Pittsburgh in western Pennsylvania, USA. No annual variation in homing performance was observed at these sites in eastern North America, in contrast to results from a number of similar experiments in Europe. Assuming pigeons home using low-frequency infrasonic signals (~0.1-0.3 Hz), as has been previously proposed, the annual and geographic variability in homing performance within the northern hemisphere might be explained, to a first order, by seasonal changes in low-frequency atmospheric background noise levels related to storm activity in the North Atlantic Ocean, and by acoustic waveguides formed between the surface and seasonally reversing stratospheric winds...
June 2016: Journal of Comparative Physiology. A, Neuroethology, Sensory, Neural, and Behavioral Physiology
S Bruce Martin, Arthur N Popper
There is a growing body of research on natural and man-made sounds that create aquatic soundscapes. Less is known about the soundscapes of shallow waters, such as in harbors, rivers, and lakes. Knowledge of soundscapes is needed as a baseline against which to determine the changes in noise levels resulting from human activities. To provide baseline data for the Hudson River at the site of the Tappan Zee Bridge, 12 acoustic data loggers were deployed for a 24-h period at ranges of 0-3000 m from the bridge, and four of the data loggers were re-deployed for three months of continuous recording...
April 2016: Journal of the Acoustical Society of America
Zhiwu Han, Zhengzhi Mu, Wei Yin, Wen Li, Shichao Niu, Junqiu Zhang, Luquan Ren
Over millions of years, animals have evolved to a higher intelligent level for their environment. A large number of diverse surface structures on their bodies have been formed to adapt to the extremely harsh environment. Just like the structural diversity existed in plants, the same also applies true in animals. Firstly, this article provides an overview and discussion of the most common functional surface structures inspired from animals, such as drag reduction, noise reduction, anti-adhesion, anti-wear, anti-erosion, anti-fog, water capture, and optical surfaces...
August 2016: Advances in Colloid and Interface Science
Stephen M Nichols, David L Bradley
Ocean surface winds play a key role in underwater ambient noise generation. One particular frequency band of interest is the infrasonic or very low frequency (VLF) band from 1 to 20 Hz. In this spectral band, wind generated ocean surface waves interact non-linearly to produce acoustic waves, which couple into the seafloor to generate microseisms, as explained by the theory developed by Longuet-Higgins. This study examines long term data sets in the VLF portion of the ambient noise spectrum, collected by the hydroacoustic systems of the Comprehensive Nuclear-Test Ban Treaty Organization in the Atlantic, Pacific, and Indian Oceans...
March 2016: Journal of the Acoustical Society of America
Peter Harris, Rachel Philip, Stephen Robinson, Lian Wang
Monitoring ocean acoustic noise has been the subject of considerable recent study, motivated by the desire to assess the impact of anthropogenic noise on marine life. A combination of measuring ocean sound using an acoustic sensor network and modelling sources of sound and sound propagation has been proposed as an approach to estimating the acoustic noise map within a region of interest. However, strategies for developing a monitoring network are not well established. In this paper, considerations for designing a network are investigated using a simulated scenario based on the measurement of sound from ships in a shipping lane...
2016: Sensors
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