keyword
MENU ▼
Read by QxMD icon Read
search

Ocean Noise

keyword
https://www.readbyqxmd.com/read/28147624/localizing-scatterers-from-surf-noise-cross-correlations
#1
Jie Li, Peter Gerstoft, Dazhi Gao, Guofu Li, Ning Wang
The backscattered travel-time structure is obtained by cross-correlating air-acoustic ocean surf noise recorded on microphone pairs (separation ∼2 m) on the beach. The scatterer is a 20 cm radius Polyvinyl chloride pipe 2.5 m landside of the microphone array. Arrivals corresponding to the time-difference (travel-time difference between two scatterer-receiver paths) and scattered (travel time for receiver-scatterer-receiver path) waves emerge in the cross-correlation functions in a backscattering configuration...
January 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28147605/adaptive-frequency-difference-matched-field-processing-for-high-frequency-source-localization-in-a-noisy-shallow-ocean
#2
Brian M Worthmann, H C Song, David R Dowling
Remote source localization in the shallow ocean at frequencies significantly above 1 kHz is virtually impossible for conventional array signal processing techniques due to environmental mismatch. A recently proposed technique called frequency-difference matched field processing (Δf-MFP) [Worthmann, Song, and Dowling (2015). J. Acoust. Soc. Am. 138(6), 3549-3562] overcomes imperfect environmental knowledge by shifting the signal processing to frequencies below the signal's band through the use of a quadratic product of frequency-domain signal amplitudes called the autoproduct...
January 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28147571/active-wideband-higher-order-raypath-separation-in-multipath-environment
#3
Longyu Jiang, Yaping Hong, Philippe Roux, Jiasong Wu, Huazhong Shu
Multiple raypaths propagation is caused by reflection and refraction at the surface and the bottom of the water column. In this study, an active wideband higher-order separation is proposed, which enables the separation of raypaths interrupted by colored noise (as traditionally found in ocean environments) in the angle-vs-time domain. A comparative study shows that the proposed algorithm achieves a more accurate separation than other algorithms. Moreover, with the proposed approach, it is not necessary to assume that the number of sensors is larger than that of the sources...
January 2017: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28076360/consequences-of-global-warming-of-1-5-%C3%A2-c-and-2-%C3%A2-c-for-regional-temperature-and-precipitation-changes-in-the-contiguous-united-states
#4
Ambarish V Karmalkar, Raymond S Bradley
The differential warming of land and ocean leads to many continental regions in the Northern Hemisphere warming at rates higher than the global mean temperature. Adaptation and conservation efforts will, therefore, benefit from understanding regional consequences of limiting the global mean temperature increase to well below 2°C above pre-industrial levels, a limit agreed upon at the United Nations Climate Summit in Paris in December 2015. Here, we analyze climate model simulations from the Coupled Model Intercomparison Project Phase 5 (CMIP5) to determine the timing and magnitude of regional temperature and precipitation changes across the contiguous United States (US) for global warming of 1...
2017: PloS One
https://www.readbyqxmd.com/read/28040049/ambient-noise-correlations-on-a-mobile-deformable-array
#5
Perry Naughton, Philippe Roux, Riley Yeakle, Curt Schurgers, Ryan Kastner, Jules S Jaffe, Paul L D Roberts
This paper presents a demonstration of ambient acoustic noise processing on a set of free floating oceanic receivers whose relative positions vary with time. It is shown that it is possible to retrieve information that is relevant to the travel time between the receivers. With thousands of short time cross-correlations (10 s) of varying distance, it is shown that on average, the decrease in amplitude of the noise correlation function with increased separation follows a power law. This suggests that there may be amplitude information that is embedded in the noise correlation function...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28040020/effect-of-dispersion-on-the-convergence-rate-for-green-s-function-retrieval
#6
John Y Yoritomo, Richard L Weaver
Much information about wave propagation in a variety of structures has been obtained from Green's function retrieval by noise correlation. Here it is examined how dispersion affects Green's function retrieval and, in particular, its signal-to-noise ratio (SNR). On recalling how the inherent spread of a signal due to band limitation is augmented by spread due to dispersion and propagation distance, and how both affect amplitude, it is argued that SNR in highly dispersive media can be substantially lowered by strong dispersion...
December 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/28036011/a-fiber-optic-interferometric-tri-component-geophone-for-ocean-floor-seismic-monitoring
#7
Jiandong Chen, Tianying Chang, Qunjian Fu, Jinpeng Lang, Wenzhi Gao, Zhongmin Wang, Miao Yu, Yanbo Zhang, Hong-Liang Cui
For the implementation of an all fiber observation network for submarine seismic monitoring, a tri-component geophone based on Michelson interferometry is proposed and tested. A compliant cylinder-based sensor head is analyzed with finite element method and tested. The operation frequency ranges from 2 Hz to 150 Hz for acceleration detection, employing a phase generated carrier demodulation scheme, with a responsivity above 50 dB re rad/g for the whole frequency range. The transverse suppression ratio is about 30 dB...
December 28, 2016: Sensors
https://www.readbyqxmd.com/read/28000727/evidence-of-cnidarians-sensitivity-to-sound-after-exposure-to-low-frequency-noise-underwater-sources
#8
Marta Solé, Marc Lenoir, José Manuel Fontuño, Mercè Durfort, Mike van der Schaar, Michel André
Jellyfishes represent a group of species that play an important role in oceans, particularly as a food source for different taxa and as a predator of fish larvae and planktonic prey. The massive introduction of artificial sound sources in the oceans has become a concern to science and society. While we are only beginning to understand that non-hearing specialists like cephalopods can be affected by anthropogenic noises and regulation is underway to measure European water noise levels, we still don't know yet if the impact of sound may be extended to other lower level taxa of the food web...
December 21, 2016: Scientific Reports
https://www.readbyqxmd.com/read/27914437/humpback-whale-generated-ambient-noise-levels-provide-insight-into-singers-spatial-densities
#9
Kerri D Seger, Aaron M Thode, Jorge Urbán-R, Pamela Martínez-Loustalot, M Esther Jiménez-López, Diana López-Arzate
Baleen whale vocal activity can be the dominant underwater ambient noise source for certain locations and seasons. Previous wind-driven ambient-noise formulations have been adjusted to model ambient noise levels generated by random distributions of singing humpback whales in ocean waveguides and have been combined to a single model. This theoretical model predicts that changes in ambient noise levels with respect to fractional changes in singer population (defined as the noise "sensitivity") are relatively unaffected by the source level distributions and song spectra of individual humpback whales (Megaptera novaeangliae)...
September 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27914391/frequency-based-noise-coherence-function-extension-and-application-to-passive-bottom-loss-estimation
#10
Lanfranco Muzi, Martin Siderius, Peter L Nielsen
Accurate modeling of acoustic propagation in the ocean waveguide is important to SONAR-performance prediction. Particularly in shallow waters, a crucial contribution to the total transmission loss is the bottom refection loss, which can be estimated passively by beamforming the natural surface-noise acoustic field recorded by a vertical line array of hydrophones. However, the performance in this task of arrays below 2 m of length is problematic for frequencies below 10 kHz It is shown in this paper that, when the data are free of interference from sources other than wind and wave surface noise, data from a shorter array can be used to approximate the coherence function of a longer array...
September 2016: Journal of the Acoustical Society of America
https://www.readbyqxmd.com/read/27807249/singing-whales-generate-high-levels-of-particle-motion-implications-for-acoustic-communication-and-hearing
#11
T Aran Mooney, Maxwell B Kaplan, Marc O Lammers
Acoustic signals are fundamental to animal communication, and cetaceans are often considered bioacoustic specialists. Nearly all studies of their acoustic communication focus on sound pressure measurements, overlooking the particle motion components of their communication signals. Here we characterized the levels of acoustic particle velocity (and pressure) of song produced by humpback whales. We demonstrate that whales generate acoustic fields that include significant particle velocity components that are detectable over relatively long distances sufficient to play a role in acoustic communication...
November 2016: Biology Letters
https://www.readbyqxmd.com/read/27770981/marine-mammals-in-the-mediterranean-sea-an-overview
#12
G Notarbartolo di Sciara
Despite being a small part of the world's oceans, the Mediterranean Sea hosts a diverse marine mammal fauna, with a total of 28 different species known to occur, or to have occurred, in the region. Species currently recognised as regular in the Mediterranean-the Mediterranean monk seal (Monachus monachus) and 11 cetaceans (fin whale, Balaenoptera physalus; sperm whale, Physeter macrocephalus; Cuvier's beaked whale, Ziphius cavirostris; short-beaked common dolphin, Delphinus delphis; long-finned pilot whale, Globicephala melas; Risso's dolphin, Grampus griseus; killer whale, Orcinus orca; striped dolphin, Stenella coeruleoalba; rough-toothed dolphin, Steno bredanensis; common bottlenose dolphin, Tursiops truncatus; harbour porpoise, Phocoena phocoena relicta) have adapted well to the region's environmental conditions, but their coexistence with humans is problematic...
2016: Advances in Marine Biology
https://www.readbyqxmd.com/read/27699134/full-field-interferometry-for-counting-and-differentiating-aquatic-biotic-nanoparticles-from-laboratory-to-tara-oceans
#13
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
https://www.readbyqxmd.com/read/27698122/simple-dynamical-models-capturing-the-key-features-of-the-central-pacific-el-ni%C3%A3-o
#14
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
https://www.readbyqxmd.com/read/27677390/shipping-noise-in-a-dynamic-sea-a-case-study-of-grey-seals-in-the-celtic-sea
#15
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...
January 15, 2017: Marine Pollution Bulletin
https://www.readbyqxmd.com/read/27631632/a-looming-bias-in-spatial-hearing-effects-of-acoustic-intensity-and-spectrum-on-categorical-sound-source-localization
#16
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)...
January 2017: Attention, Perception & Psychophysics
https://www.readbyqxmd.com/read/27611092/exploring-the-effect-of-sound-and-music-on-health-in-hospital-settings-a-narrative-review
#17
REVIEW
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
https://www.readbyqxmd.com/read/27586608/finite-time-lyapunov-exponent-based-analysis-for-compressible-flows
#18
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
https://www.readbyqxmd.com/read/27506974/is-the-detection-of-accelerated-sea-level-rise-imminent
#19
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
https://www.readbyqxmd.com/read/27475213/head-wave-correlations-in-ambient-noise
#20
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
keyword
keyword
11541
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"