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A key question related to regulating noise from pile driving, air guns, and sonars is how to take into account the hearing abilities of different animals by means of auditory frequency weighting. Recordings of pile driving sounds, both in the presence and absence of a bubble curtain, were evaluated against recent thresholds for temporary threshold shift (TTS) for harbor porpoises by means of four different weighting functions. The assessed effectivity, expressed as time until TTS, depended strongly on choice of weighting function: 2 orders of magnitude larger for an audiogram-weighted TTS criterion relative to an unweighted criterion, highlighting the importance of selecting the right frequency weighting. (C) 2017 Acoustical Society of America

Biosonar is vital to odontocetes (toothed whales, dolphins, and porpoises) for navigation and finding food. Consequently, numerous details of their echolocation click parameters, such as source level and beam width, are known for many species; however, there is a data gap for killer whales (Orcinus orca). This information is essential for examining masking potential which could have an impact on their foraging abilities. The Southern Resident killer whales are an endangered population of orcas living along the Pacific coast of North America and underwater noise has been identified as a major threat towards their survival. This study used a 3D 24-element hydrophone array deployed in close proximity to wild killer whales to estimate source levels (SLs) and spectra of echolocation clicks. Future work will use these SLs to investigate masking potential from current and other noise scenarios.

The results of ambient sea noise measurements performed in strongly stratified shallow basins in the southern Baltic Sea are presented. The experiments were conducted with an autonomous hydroacoustic buoy that was equipped with two omnidirectional hydrophones located inside and outside the seasonal waveguide. Data were collected in two areas with contrastingly diverse sound propagation conditions-at the Bornholm Deep in winter and at the Gdansk Deep in summer. The noise spectrum levels indicate a strong dependence on the sound propagation conditions (season, location) and show significant differences with the observation depth. At frequencies f

Underwater noise measurements were made adjacent to the Monitor-Merrimac Memorial Bridge-Tunnel in the James River, VA during a field experiment in April of 2019. Anticipated sources of underwater noise included wind, waves and associated bubbles, flow noise, boat/ship traffic, industrial shipyard noise and traffic noise radiating from the underwater tunnel. During the field observations, winds, waves/surface conditions, underwater currents, water column structure and tunnel traffic were monitored by anemometers, high-frequency surface radar, ADCPs, echosounders and traffic sensors. The observed noise field exhibited high frequency and tidal-scale variability due to passing surface vessels and tidally driven currents in the estuary; most interestingly, the noise field exhibited variability on a diurnal time scale, closely correlated to the temporal distribution of vehicular traffic in the underwater tunnel. The tunnel traffic underwater noise amplitude varied by 1–5 dB at 10s to 100s of Hertz and exhibited a non-linear relationship to frequency.

ANSI and ISO have issued standards for the measurement of the radiated noise level of surface vessels in deep water. In addition, a draft standard for the conversion of such measurements into a monopole source level, as required for environmental noise models, is at an advanced stage. However, many operators and investigators are constrained to making measurements in shallow water where both sea-surface and seabed effects are important. In order to study the influence of these effects a numerical study has been performed using both an image source model and OASES, with very good agreement. The goal of this work has been to understand the variability of the correction factor required to convert measurements of received pressure, at short range, into the equivalent source level in such an environment. These calculations have included the effects of reflection at both the sea-surface and an attenuating seabed. The influences of the water depth, seabed type, distance of closest approach, and number and location of the hydrophones have been investigated. The results show how the correction factor varies and indicate the extent to which simplified approximations can be used for the correction factor.

The increased interest in the potential environmental impact of noise from shipping is resulting in the development of measurement methods for determining the radiated noise level and equivalent monopole source level of vessels. It is important to understand the random and systematic uncertainties associated with such techniques. The EU SONIC project provided an opportunity to make repeated measurements on the University of Newcastle research vessel, the Princess Royal, in a shallow water environment (100 m deep) over a number of days. Two multiple hydrophone arrays operated by two of the project partners, CETENA and the University of Southampton, were deployed from the same moored support vessel. This data is reviewed to illustrate the variation associated with such measurements and the impact of using multiple hydrophones and multiple measurement runs on the uncertainty in the radiated noise level and the calculated source level. The results are also compared with a later measurements of the same vessel in a different shallow water environment (20 m deep) using bottom moored hydrophones.

An approach for the prediction of underwater noise caused by impact pile driving is described and validated based on in situ measurements. The model is divided into three sub-models. The first sub-model, based on the finite element method, is used to describe the vibration of the pile and the resulting acoustic radiation into the surrounding water and soil column. The mechanical excitation of the pile by the piling hammer is estimated by the second sub-model using an analytical approach which takes the large vertical dimension of the ram into account. The third sub-model is based on the split-step Padé solution of the parabolic equation and targets the long-range propagation up to 20 km. In order to presume realistic environmental properties for the validation, a geoacoustic model is derived from spatially averaged geological information about the investigation area. Although it can be concluded from the validation that the model and the underlying assumptions are appropriate, there are some deviations between modeled and measured results. Possible explanations for the observed errors are discussed.

Offshore piling for wind farm construction has attracted a lot of attention in recent years due to the extremely high noise emission levels associated with such operations. While underwater noise levels were shown to be harmful for the marine biology, the propagation of airborne piling noise over sea has not been studied in detail before. In this study, detailed numerical calculations have been performed with the Green's Function Parabolic Equation (GFPE) method to estimate noise levels up to a distance of 10 km. Measured noise emission levels during piling of pinpiles for a jacket-foundation wind turbine were assessed and used together with combinations of the sea surface state and idealized vertical sound speed profiles (downwind sound propagation). Effective impedances were found and used to represent non-flat sea surfaces at low-wind sea states 2, 3, and 4. Calculations show that scattering by a rough sea surface, which decreases sound pressure levels, exceeds refractive effects, which increase sound pressure levels under downwind conditions. This suggests that the presence of wind, even when blowing downwind to potential receivers, is beneficial to increase the attenuation of piling sound over the sea. A fully flat sea surface therefore represents a worst-case scenario.

In humans, excessive noise exposure from occupational or recreational sources causes permanent hearing loss. Similarly, exposure to underwater anthropogenic noise can cause hearing loss in aquatic organisms, including fish. While fish can recover from noise-induced hearing loss, underwater noise exposure can cause behavioral changes that reduce organismal fitness. In all vertebrates, acoustic trauma can cause damage to sensory hair cells. To better study the effects of noise on hair cells, we have developed a noise exposure system that uses broadband sound to damage hair cells of the inner ear and lateral line of larval zebrafish. Acoustic over-exposure kills hair cells in an intensity- and time-dependent manner, with maximum hair cell damage observed 72 hours after noise exposure. This time course is consistent with mammalian studies, where hair cell death occurs days to weeks after noise exposure. Other features of acoustic trauma are also conserved between zebrafish and mammals, including activation of apoptotic signaling cascades and changes in hair cell-afferent synapses. These studies demonstrate that larval zebrafish are a tractable new model for studies of noise-induced hair cell death. However, our acoustic trauma system could also be used in other species, allowing for new studies of underwater noise in larval fishes.

Underwater acoustic recordings of six Floating Production Storage and Offloading (FPSO) vessels moored off Western Australia are presented. Monopole source spectra were computed for use in environmental impact assessments of underwater noise. Given that operations on the FPSOs varied over the period of recording, and were sometimes unknown, the authors present a statistical approach to noise level estimation. No significant or consistent aspect dependence was found for the six FPSOs. Noise levels did not scale with FPSO size or power. The 5th, 50th (median), and 95th percentile source levels (broadband, 20 to 2500 Hz) were 188, 181, and 173 dB re 1 μPa @ 1 m, respectively.

This paper presents the empirical probability density of the power spectral density as a tool to assess the field performance of passive acoustic monitoring systems and the statistical distribution of underwater noise levels across the frequency spectrum. Using example datasets, it is shown that this method can reveal limitations such as persistent tonal components and insufficient dynamic range, which may be undetected by conventional techniques. The method is then combined with spectral averages and percentiles, which illustrates how the underlying noise level distributions influence these metrics. This combined approach is proposed as a standard, integrative presentation of ambient noise spectra.

This introductory talk will address why underwater acoustics are important, its uses, how sound propagates so far in the ocean, man-made sounds, including shipping noise, and the impact of noise in the ocean. A short overview of organizations working on the issue of underwater noise will be given including those around the Salish Sea where the conference is being held. The way sound is measured and analyzed will be shown with local examples of marine life, earthquake and anthropogenic noise. A short exercise to show the effects of acoustic masking will be given, followed by an explanation of echolocation use by the Southern Resident Killer Whales and the implications of acoustic masking on finding food for this local and endangered species.This introductory talk will address why underwater acoustics are important, its uses, how sound propagates so far in the ocean, man-made sounds, including shipping noise, and the impact of noise in the ocean. A short overview of organizations working on the issue of underwater noise will be given including those around the Salish Sea where the conference is being held. The way sound is measured and analyzed will be shown with local examples of marine life, earthquake and anthropogenic noise. A short exercise to show the effects of acoustic masking will be given, followed by an explanation of echolocation use by the Southern Resident Killer Whales and the implications of acoustic masking on finding food for this local and endangered species.

This paper presents results from year-long passive acoustic recordings in the seasonally ice-covered ocean north of Spitsbergen (Svalbard archipelago) from July 2016 to June 2017. Two moorings were deployed by FFI, each with an AMAR Ultra Deep acoustic recorder (JASCO Applied Sciences) equipped with a single hydrophone. The moorings were deployed and retrieved during open-water conditions and remained during periods of partially to near fully ice-covered conditions. We present results from analysis of the acoustic data for ambient noise spectra and statistics, and discuss characteristics of the spectra in relation to environmental factors including ice cover, wind and ocean waves. Seasonal noise spectra are compared with historic measurements from the eastern Arctic. Components of the sound field including transients due to ice, marine mammals, and anthropogenic noise will also be discussed.

Shipping noise has been identified as a threat on underwater ecosystems. In particular, several impacts have been documented on cetaceans, e.g., communication’s masking and stress increasing. To assess the risk related to such anthropogenic noise requires both quantifying the noise levels and estimating the distribution of the cetaceans’ population. However, current methods evaluating the risks related to anthropogenic pressures generally rely on strong expert priors, which may be difficult to define. This presentation aims at introducing a new framework for the comparison of anthropogenic pressure levels maps and cetaceans’ distribution in order to infer the risk of impact and provide management solutions. The methodology, combining simple statistical analyses and a theoretical representation tool was applied to the Bay of Biscay using shipping noise model and fin whale observation from regular surveys for the years 2012 and 2016. Relationships between cetaceans’ distribution and noise levels were investigated and linked to mammals theoretical responses to pressure. A trend analysis between 2012 and 2016 was also proposed to identify the noise hotspots. The results were interpreted in both terms of ecological meaning for fin whale and conservation measures for shipping noise, according to marine policies requirements.

The increase of oceanic shipping is a global predicament. The resulting proliferation of underwater noise levels is a serious concern for marine mammal welfare, as it has the potential to interfere with the communicative signals of bottlenose dolphins (Tursiops truncatus). The Lombard effect and other noise-induced vocal modifications may be employed to compensate for reduced signal-to-noise ratios. This study aimed to determine which vocal modifications dolphins use during experimentally controlled background noise conditions. Three dolphins (ages 30–52) participated in behavioral hearing tests using an adaptive up-down staircase, go/no-go procedure with 15 or 40 kHz tones. Tones decreased by 3 dB increments if a dolphin responded to the tone with a conditioned whistle, and increased by 3 dB if they did not. Dolphins performed this task during ambient noise (control) conditions, as well as three elevated bandpass noise (experimental) conditions: 0.6–5 kHz (115 dB re 1 μPa) and 0.6–10 kHz (115 and 125 dB re 1 μPa). The acoustic parameters of the dolphins’ response whistles and victory squeals, such as duration, frequency, amplitude, and response latency, were analyzed and compared between control and noise conditions. These data provide a complement to field studies of odontocete noise-induced vocal modifications in the wild.

Measurements of temporary threshold shift (TTS) in marine mammals have become important components in developing safe exposure guidelines for animals exposed to intense human-generated underwater noise; however, existing marine mammal TTS data are somewhat limited in that they have typically induced small amounts of TTS. This paper presents experimental data for the growth and recovery of larger amounts of TTS (up to 23 dB) in two bottlenose dolphins (Tursiops truncatus). Exposures consisted of 3-kHz tones with durations from 4 to 128 s and sound pressure levels from 100 to 200 dB re 1 μPa. The resulting TTS data were combined with existing data from two additional dolphins to develop mathematical models for the growth and recovery of TTS. TTS growth was modeled as the product of functions of exposure duration and sound pressure level. TTS recovery was modeled using a double exponential function of the TTS at 4-min post-exposure and the recovery time.

The marine environment faces a pressure from the increasing shipping intensity in the form of rising levels of continuous anthropogenic underwater noise. Current underwater noise monitoring guidelines advise to measure the long-term trends in the overall noise levels in the frequency bands where ship noise is most prevalent. However, the natural noise is omnipresent and prolongs the time period required for the detection of statistically significant trends in the overall noise. The monitoring efficiency can be improved by finding the proportions of the anthropogenic and the natural noise levels and by measuring the changes in the proportions over time. These proportions can be found by differentiating between the different types of ambient noise in the recordings according to both proximity of the ships and the variability of the environmental conditions. This is achieved by using the AIS ship traffic data along with the ship noise detection algorithms. The AIS data enables determination of the position of ships around a noise monitoring location and calibration of the ship noise detection algorithms. The results and the methods are presented for the passive acoustic monitoring in the Baltic Sea and applicability of the described methods are discussed.

A study is presented of the acoustic signals produced by raindrops impacting on the surface of water contained in a sensor assembly. The impact generates low frequency damped pressure waves in water. The low frequency spectrum of this signal is seen to be fairly consistent and is used for measuring the kinetic energy of the raindrops from which the drop-size distribution and the rain intensity are estimated. The proposed method is computationally efficient and can be implemented with simple DSP hardware.

This paper investigates the acoustic behavior of free flooding resonators consisting of inverted cups that are lowered into a water column such that a volume of air is entrapped within the cavity upon submersion. Similar to a two-fluid Helmholtz resonator, the resonance frequency is determined by the compliance of the entrapped air and the radiation mass of water at the opening of the cavity. The entrapped air mass is compressed as the resonator is lowered to depth due to the increase in hydrostatic pressure, which affects the acoustic behavior. Collections of similar resonators with compliant walls were previously investigated for use in underwater noise abatement [Lee et al., Proc. Meeting Acoustics 22, 045004 (2015)]; however, recent work has shown an increase in quality factor and attenuation performance for stiffer walled resonators. Measurements were taken to determine the resonance frequencies and quality factors of both individual resonators and arrays of resonators comprised of various wall mater...

Anthropogenic underwater sounds can impact aquatic life. Adherence to the Marine Mammal Protection Act (MMPA), the Endangered Species Act (ESA), and the Magnuson-Stevens Fishery Conservation and Management Act (MSA) requires a risk assessment of the potential effects from underwater noise. Procedures for evaluating the risk to marine mammals (MMPA) are increasingly sophisticated, and quantitative science-based criteria for mammals were published in 2007 by Southall et al. The need for equivalent criteria for fishes and sea turtles (ESA and MSA) led to the creation of our expert working group co-led by Professors Arthur Popper and Richard Fay, pillars in the USA for everything fish. While Professor Tony Hawkins, a pillar in the EU for everything fish, brought his own unique perspectives and broad expertise of fish hearing studies and sound exposure. The results from our working group are described from its inception in 2004 to the 2014 publication of its findings as an ANSI/ASA report. The report determine...

During his research career spanning over 40 years, Arthur Popper has had a profound impact on the field of bioacoustics. He studied a broad range of vertebrate taxa, focusing on fish, but also including amphibians, reptiles, and mammals, and published over 200 papers. His work has improved our knowledge of the morphology of vertebrate inner ears and has made significant advances to our understanding of the evolution of vertebrate hearing. In recent years Dr. Popper has focused his research on the important question of how underwater noise impacts aquatic vertebrate hearing. A long standing and fruitful collaboration with his friend and colleague, Richard Fay, has resulted in numerous scientific papers and nearly 60 books including the well-known SHAR-series of the Springer Handbook of Auditory Research.

Underwater noise is a growing concern to conservation and stock management efforts to which supra-national organizations (e.g., OSPAR or the European Union) and governments (e.g., USA) are beginning to respond by building catalogues of the noise introduced in the marine environment by human activity. Rock placement is a construction activity for which there is scarcely any data available. In order to fill the knowledge gap, opportunistic recordings were taken while the Gardline Mk 3 hydrophone array was deployed for Passive Acoustic Monitoring and mitigation for marine mammals. The recordings were analysed for their spectral and temporal characteristics, a correlation analysis between the amount of rock placed and the intensity of sound produced was made and the suitability of the hydrophone array for the collection of this type of data was assessed.

It has been my experience with both traditional print journalists, and with modern media journalists, that unexpected interactions and outcomes sometimes occur. These can have both desirable and undesired consequences for the scientist. Some examples of these interactions will be given, which are associated with quite diverse technical topics, ranging from press and radio interviews covering work on the soundscape of a threatened species (Ceratotherium simum simum, the southern white rhinoceros), to a radio interview on the acoustics of coffee roasting that included a surprise guest, to an underwater photo shoot with a National Geographic photographer covering research on an underwater noise abatement system. Some guidelines will be presented that aim to minimize the undesired outcomes.

A drop of water falling on a water surface entrains a bubble for certain drop diameter–impact velocity combinations. Volume oscillations of the bubble contribute to the underwater noise of rain. A method was developed for optical detection of these volume oscillations in a laboratory environment. The entrained bubble is in the path of a laser beam when the bubble is created. The beam is then directed to a photodetector and the transient signal resulting from oscillations of the optical cross section of the bubble is recorded. This optically obtained record is compared to an acoustic record of each event and the frequencies are in agreement. The general magnitude of the initial radial oscillation is estimated and compared with relevant theoretical results by Oguz and Prosperetti [J. Fluid Mech. 228, 417–442 (1991)].

This paper is a continuation of an earlier one [Prosperetti et al., J. Acoust. Soc. Am. 93, XXX (1993)] in which the low‐frequency backscattering of sound by hemispherical bubble clouds at the ocean’s surface was studied. Here, clouds of various geometrical shapes (spheroids, spherical segments, cones, cylinders, ellipsoids) are considered and results in substantial agreement with the earlier ones and with the experiments of Chapman and Harris [J. Acoust. Soc. Am. 34, 1592–1597 (1962)] are found. The implication is that the backscattering levels are not strongly dependent on the shape of the clouds, which strengthens the earlier conclusion that bubble clouds produced by breaking waves can very well be responsible for the unexpectedly high backscattering levels observed experimentally. The accuracy of the Born approximation used by others for similar problems is also examined in the light of the exact results. Significant differences are found for gas concentrations by volume of the order of 0.01% or highe...

As offshore wind energy development increases across the eastern seaboard, there is a growing need to determine the short and long-term effects of activities associated with this development on marine ecosystems. One area of particular importance is the potential effects of underwater noise on marine life. To better characterize underwater sound levels associated with geotechnical activities, a hydroacoustic measurement program of geotechnical survey activities was completed in support of Dominion’s Virginia Offshore Wind Technical Advancement Program. An important component of this project was the advancement of new technologies and the use of best available science to collect data for more accurate impact determinations. The overall goal of the hydroacoustic measurement program was to field-verify the projected acoustic impacts during geotechnical activities. This new insight will support both decision making in the execution of offshore wind site characterization surveys, and reduce the potential for future impacts. Measurements were made using a combination of equipment including a cabled real-time hydroacoustic analysis systems and fixed autonomous static recorders. Upon conclusion of the hydroacoustic survey, data were downloaded and directly correlated with daily activity logs from the vessels used in performing the offshore geotechnical work thereby providing the means to coordinate acoustic events.

An international workshop was held in 2013 with a group comprised of scientists, regulators, and other stakeholders. The workshop focused on how new scientific information related to the effects of underwater noise on marine life influences permitting practices for human activities at sea. Also discussed were how individual countries regulate underwater noise and opportunities for harmonizing approaches on an international scale. The workshop was intended to build momentum toward an international exchange of information and to potentially establish a network for the regulation community. Large gaps in knowledge still exist. In particular, hearing sensitivity in baleen whales, long-term effects of TTS and relevant information on other taxa such as bony fishes, sharks, or invertebrate species, need to be studied more intensively. Regulators need reliable and understandable baseline information on cause-effect relationships. This information could be partially provided through targeted training material for regulators. Another critical regulator need is for opportunities to speak with each other and share knowledge across wide geographic regions. Additional keys to future success are commitments from the regulatory senior management and politicians, invite nations who were not represented in the discussions so far and raise awareness of this topic across a broad audience, including the public.

Man-made sounds in ocean and inland water environments become biologically significant when they affect the ability of animals and fish to survive and reproduce. Extremely strong sounds produced by pile driving can highly exceed the environmental safety limits and application of bubble curtain is one of the most effective methods for sound suppression. We present several physical models explaining sound suppression by bubble curtain and discuss the methods of improving bubble curtain efficiency. The physical models of sound suppression by a bubble curtain include: (a) Estimation of bubble curtain impedance leading to decreasing of the pile drive acoustic coupling with surrounding bubbly water and (b) theoretical model for the estimation of sound attenuation by resonance bubbles. The developed models were analyzed for the optimization of the pile drive sound suppression. Several methods for generating a bubble curtain with small bubbles and bubbles with varied sizes are considered. We also suggest a way for improving the efficiency of bubble curtains by increasing the lifetime of the bubbles using bubble coating. Coated micro bubbles are widely used as ultrasound contrast agents in cardiology. One of the simplest ways for micro bubble coating is the passing of bubbles through oil.

Arrays of large encapsulated bubbles are currently under development for the purpose abating low-frequency anthropogenic underwater noise from various sources including marine pile driving and oil and gas exploration and production. An existing predictive model [Church, J. Acoust. Soc. Am. 97, 1510–1521 (1995)], which was originally intended to describe propagation through suspensions of microbubbles used as ultrasound contrast agents, was previously found to be in good agreement with resonance frequency and attenuation measurements using large encapsulated with radii on the order of 10 cm [Lee et al., J. Acoust. Soc. Am 132, 2039 (2012); Lee and Wilson, Proceedings of Meetings on Acoustics 19, 075048 (2013)]. For the current study, both laboratory and lake experiments were performed on large encapsulated bubbles to investigate the dependence of the bubbles’ resonance frequencies and attenuation on the bubble wall thickness. Additionally, laboratory measurements were made to investigate the effects on encapsulated bubble resonance frequencies and damping using bubble fill-materials other than air, and a lake experiment was then performed to relate these effects on the damping to the attenuation provided by arrays of such bubbles. [Work supported by AdBm Technologies.]

There is concern that underwater noise generated by marine construction activities and radiated by towers supporting offshore wind turbines may disturb marine mammals, or interfere with passive sensors and communication equipment. In order to understand these effects a semi-analytic frequency-domain model was developed previously for the sound radiated in the water column by a pulsating cylindrical structure embedded in horizontally stratified layers of viscoelastic sediment. This model was in turn coupled to a parabolic equation code for long-range propagation over range-dependent environments [Hay et al., J. Acoust. Soc. Am. 133, 3396 (2013)]. A time-domain version of this model is now presented which enables simulation of impulsive sound sources such as those due to underwater pile driving, and pulsed tonal sources appropriate for use in a finite-sized laboratory tank. In order to validate the model a scaled physical model, consisting of a laboratory tank and metallic cylindrical tube driven in the high kilohertz frequency range, was constructed. Simulations will be presented for a variety of sound sources, and preliminary comparisons with measurements from the scaled model experiments will be made.

The ultimate goal of this work is to accurately predict the attenuation through a collection of large (on the order of 10 cm radius) tethered encapsulated bubbles used in an underwater noise abatement system. Measurements of underwater sound attenuation were performed during a set of lake experiments, where a low-frequency compact electromechanical sound source was surrounded by different arrays of encapsulated bubbles with various individual bubbles sizes and void fractions. The measurements are compared with an existing predictive model [J. Acoust. Soc. Am. 97, 1510--1521 (1995)] of the dispersion relation for linear propagation in liquid containing encapsulated bubbles. Although the model was originally intended to describe ultrasound contrast agents, it is evaluated here for large bubbles, and hence low frequencies, as a design tool for the underwater noise abatement system, and there is fairly good quantitative agreement between the data and the model. Refinements to the model to incorporate multiple scattering effects, which may be important at high void fractions, via an effective medium approach [J. Acoust. Soc. Am. 111, 168--173 (2002)] and comparison with the data will also be discussed. [Work supported by Shell Global Solutions.]

A stand-off curtain of encapsulated bubbles with resonance frequencies of approximately 50 Hz was used to attenuate radiated noise from a work barge vibrated by onboard rotating machinery in a lake experiment. The purpose of this experiment was to provide a scale-model of how a noise reduction system of tethered encapsulated bubbles would be deployed to mitigate noise from a shallow water drilling ship. The work reported here is an extension of previous tests which used an array of encapsulated bubbles attached directly to the bottom of the work barge to reduce the radiated sound levels [J. Acoust. Soc. Am. 131, 3506 (2012)]. The design of the new stand-off encapsulated bubble curtain is described, including the finite-element model that was developed to aide in the design. The deployment and acoustic testing of the curtain are also described. Results from the tests demonstrate that the system is both practical to deploy and is effective in reducing the underwater noise radiated into the lake from the work barge. [Work supported by Shell Global Solutions.]

The author served as the chairman of the working group that completed the first voluntary consensus standard for measurement of underwater noise from ships (ANSI/ASA S12.64-2009/Part 1, Quantities and Procedures for Description and Measurement of Underwater Sound from Ships, Part 1; General Requirements). Within the last year, an effort to bring this standard to the international arena has started. The S12.64 standard is an entirely new document without any prior written standards to use as a template, however, the methodology was previously used by the U.S. Navy and NOAA. This session will address the process of organizing and developing a new ASA/ANSI standard and then taking such a standard to International Standards Organization (ISO). It will address organizational challenges of working with experts from industry, government, and academia, both from the United States. and overseas. It will cover issues related to planning and executing physical and web enabled meetings. Lastly, it will address the similarities and differences of the standards development process under ISO.

Development of computational models to predict underwater noise from impact pile driving is limited because of the difficulty and cost involved in collecting acoustic field data for model verification during construction activities. To alleviate this situation, a scaled physical model for marine pile driving was designed and implemented in a 500-gallon shallow water tank, 3.5 m long and 0.85 m wide. The scaled piles are steel pipes having lengths up to 1 m, and radius-to-wall thickness and length-to-radius ratios similar to large cast-in-shell steel (CISS) piles. The wavelength-to-depth ratio for the primary breathing mode of the fully submerged scaled piles and a fully submerged CISS pile of diameter 2.4 m and length 30 m is between 2.0 and 2.5. The impact force is generated and measured with an impulse hammer, and sound field data are collected using a small 2-D hydrophone array. Data are correlated with the results of numerical and analytical models developed to predict sound radiation from CISS piles ...

There is mounting concern over the effect of ship noise on marine mammals; however, limited empirical data quantifying this noise impede our ability to evaluate impacts. An opportunistic approach for measuring radiated ship noise (20–1000 Hz) was used in this study. Calibrated acoustic data were combined with archived information on seven types of modern merchant ships transiting the coast of southern California. Three metrics for describing ship noise were applied: received sound levels (RLs) during 1 h passages, estimated source levels (SLs), and sound exposure levels (SELs). 1 h passages provided an estimate of the spatial extent of ship noise. At 40 Hz, container ships elevated noise above background up to 7 km forward of the ship and 19 km aft; bulk carriers elevated noise above background up to 5 km at bow and stern aspects. These ship‐types had similar broad band estimated SL, 186 dB re 1 μPa at 1 m. The cumulative exposure to ship noise varied by ship type; we presented equations for estimating SELs for specific ship types. In concert, these metrics create a tool for quantifying ship noise within coastal marine environments, and can be used to assess the impact of ship noise on marine mammals. [This work was supported by the U.S. Navy CNO N45 and additional funds from the ONR, the NOAA, and the NSF.]

Marine piling is the most commonly used method for the installation of offshore wind turbines in the shallow coastal waters in the UK and consists of steel mono‐piles being driven into the seabed using powerful hydraulic hammers. This is a source of impulsive sound, of potentially high level, that can travel a considerable distance in the water column and has the potential for impact on marine life. This presentation describes methodologies developed for measurement of marine piling and for the estimation of the energy source level. Measurements are presented for piles of typically 5 m in diameter driven by hammers with typical strike energies of 1000 kJ. Data were recorded as a function of range from the source using vessel‐deployed hydrophones, and using fixed acoustic buoys that recorded the entire piling sequence, including soft start. The methodology of measurement is described along with the method of estimation of the energy source level. Limitations and knowledge gaps are discussed.

After several decades of research, wave energy has reached a pre‐commercial stage, emerging as a potential industry for the future. Despite the wave energy being considered as an environmentally friendly activity, it will probably have positive and negative aspects. The marine environment is an important area of biological diversity, hence the concern about the possible effects of underwater noise has increased among developers and promoters. While it is not expected that each individual device will produce a high level of noise, the deployment of several devices in the same farm, operating day and night, may have an effect on the fauna. However, the acoustic characterization of wave energy devices (WEDs) is not trivial; the noise generated and propagation will depend on oceanographic characteristics and operational conditions. The acoustic signature of each WED is expected to be produced from a variety of different components (mechanical or other moving parts) related to the device itself or by its inter...

Prior to 2010, the International Council for the Exploration of the Seas (or ICES) is the only organization to have developed and specified underwater (radiated) noise limit for commercial research vessels. European vessels were among the first to be built to this specification, which was given in a 1995 report. Since 2004, the US has built five ICES capable vessels, four of which were Fishery Research Vessels (FRV) for the National Oceanic and Atmospheric Administration (NOAA). In the US two more ICES capable vessels are in construction, another two are under consideration, and another three vessels are being built to an underwater noise requirement similar to ICES. This paper discusses the types of propulsion, machinery elements, and noise control features that are required in these vessels in order to meet the ICES underwater noise requirement. Design features and results will be presented from two specific, new vessel construction programs. The first is the NOAA FRV‐40 program, which resulted in four fishery research vessels built at VT Halter Marine in Pascagoula, MS. The second program was for a smaller single research vessel for the University of Delaware.

Owning and maintaining an aquarium is a common hobby, but some aspects of proper animal husbandry in the hobby community have received little scientific attention. Specifically, the ambient noise in aquariums resulting from pumps, filters, bubblers and other equipment is not well studied, yet elevated ambient noise levels have been shown to adversely affect fish and marine invertebrates. Anecdotal evidence suggests that this may be a problem in aquariums as well. Salt water aquariums designed to maintain coral reefs require high water flow and pristine water conditions, which in turn require pumps and filters that contribute to underwater noise. A survey of ambient noise in both fresh and saltwater aquariums ranging in size from 10 to 500 gallons was conducted. The aquariums differed in construction material, number, size and type of pumps, and presence of other equipment, and their ambient noise broadband levels are shown to vary widely.

The underwater noise that is produced by the underwater complex shell structure is a basic question to be solved for the noise control of an underwater structure. One way to study and control the underwater noise of the underwater complex shell structure is the experiment of vibration and sound radiation of all kinds of scaled‐down models for its prototype. This method can predict vibration and sound radiation of an underwater complex shell structure, and provides the necessary parameters for the design of noise control. Using the finite‐element method and the spherical function spread method, this paper investigates the similitude of coupled vibration and acoustic radiation for the typical structure of an underwater vehicle (elastic ring‐stiffened cylindrical shell with hemispherical caps on the ends), and presents acoustic similitude conditions and relationships of the structures. At the same time, the acoustic scale effect and boundary effect, which are influenced by loss factors, shear and rotatory in...

The regulation of noise from offshore activities in the UK requires a metric allowing the behavioral effects on underwater animals of man‐made underwater noise on a wide range of species to be objectively assessed. The dBht(species) metric is a pan‐specific metric incorporating the concept of ‘‘loudness’’ by using a frequency‐weighted curve based on the species’ hearing threshold as the reference unit for a dB scale. A large number of controlled laboratory measurements have been made of the avoidance of a range of idealized noises, using fish with greatly different hearing as a model. Additional data, of many thousands of individuals, has been obtained by re‐evaluation of fish avoidance of a large acoustic fish deflection system at an estuarine power station. All data, irrespective of source or species, indicate a dependence of avoidance reaction on the dBht(species) level. The data indicates three regions, ‘‘no reaction’’ below 0dBht (i.e., below the species’ threshold of hearing), a ‘‘cognitive avoidanc...

The NOAA Ship OSCAR DYSON is the first‐in‐class fisheries research vessel (FRV) designed and built for National Oceanic and Atmospheric Administration (NOAA) for fish stock assessment. One of its most important contractual requirements was to meet the underwater noise limit of 1995 International Council for the Exploration of the Seas (ICES) report. This paper describes the efforts to conduct the underwater noise tests of the vessel. A commercial underwater measurement system was developed which was set‐up off the Gulf of Mexico. The system consists of a small hydrophone array, signal conditioning, and data acquisition hardware. Field calibration was performed. Requirements for mounting the hydrophones and operation of a support vessel are discussed. In addition to measuring underwater sound, the distance between the source and receiver was also measured. Results are compared to the specification requirements and subsequent measurements performed by the U.S. Navy.

When the effects of underwater noise on marine mammals became a national issue in the 1990’s, the federal government needed people trained in those fields to manage programs. No trained managers with that background existed, so a few scientists took on management roles. Of today’s five Washington, DC managers in this issue, three received advanced degrees under Ron Schusterman. One started ONR’s comprehensive research program on this topic, and two run NMFS’s regulatory policy program on acoustics. Dr. Schusterman intended his students to work in basic science, specifically cognition, learning, sensory perception, and social behavior of marine mammals. Ironically, and despite his aversion to bureaucracy, this background equipped his students to become government decision makers. Such are the twists of history. He also taught his students to rigorously apply the scientific method and to assume nothing. If his science castaways in Washington, DC are worthy of his training, the national noise issue will be t...

Acoustical rainfall analysis (ARA) will provide the means to make needed rainfall measurements in oceanic regions. A prototype ARA algorithm will be presented. It consists of (1) the detection of rainfall in the presence of other underwater noise sources, (2) the classification of rainfall type based on drop size distribution, and (3) the acoustic quantification of rainfall rate. Historical data will be presented to document the acoustic detection of rainfall in oceanic situations. Recent field data demonstrating acoustic classification of rainfall type will be presented and explained using laboratory studies of sound produced by individual raindrops. Classification of rainfall type (stratiform/convective) will allow meteorologists to infer the vertical distribution of latent heat release in the atmosphere. Quantification of rainfall rate can be achieved by several different types of algorithms. Selected quantification algorithms will be presented, compared, and evaluated.

Marine anthropogenic noise is increasing at an unknown rate yet its effects on mammals and turtles are poorly documented. Such information is central to noise standards for marine animals required by two federal laws (MMPA and ESA). Good policy on underwater noise would set standards that are neither too liberal (thereby threatening the well being of marine animals), nor too conservative (thereby unnecessarily impairing essential human activities at sea). This balance must be found using existing data; standards cannot await new research. Policy must also lay out rules governing the introduction of novel underwater sound sources whose effects on animals are unknown. Should policy forbid such introductions until all possible consequences are known, or does a safe, incremental method of introduction exist? Should exceptions be made for novel sources associated with national defense? Policy must cope with sound sources that are outside the reach of U.S. federal regulations, such as international shipping. Finally, policy must frame the questions about underwater noise in a way that research can answer. Specifically, how much noise exists, how fast is it growing, where is it, and what consequences does it have for animals and their ecosystems?

The ability of a fish to interpret acoustic information in its environment is essential for survival. Thus it is important to understand how underwater noise, from anthropogenic sources such as boats, affects fish hearing. In this study, the fathead minnow, Pimephales promelas, was used to examine the following: (1) the immediate effects of white‐noise exposure (300–4000 Hz, 142 dB re: 1 μPa) on auditory thresholds; (2) recovery time of hearing ability after exposure; and (3) the effects of noise exposure, from a small boat engine recorded in the field, on hearing thresholds. Audiograms were measured using the auditory brainstem response (ABR) protocol and compared to fathead minnows not exposed to noise. Immediately after exposure to white noise, five out of the eight frequencies tested showed a significantly higher threshold compared to the control fish. Recovery was found to depend on both duration of noise exposure and auditory frequency. Boat engine noise, peak frequency of 1292 Hz, also elevated thresholds in the fathead’s most sensitive hearing range (1000–2500 Hz). These results support the hypothesis that auditory thresholds can be altered by noise in the environment and provide evidence to show that these effects can be long term (>14 days). [Work supported by the Kentucky Academy of Science.]

Acoustic energy introduced by fishing vessels into the water has been measured and analyzed. Catch records have been obtained for those boats whose acoustic characteristics are known. Averaging procedures were applied to catch records to obtain a meaningful average catch rate. This average catch rate is correlated with the spectrum of sound introduced into the water by the boat. A negative correlation between catch rate and frequencies above 1500 Hz has been established. Spectral peaks above 1500 Hz are attributed to propeller shaft bearings.

The results of recent ambient‐noise investigations, after appropriate processing, are compared on the basis of pressure spectra in the frequency band 1 cps to 20 kc. Several possible sources are discussed to determine the most probable origin of the observed noise. It is concluded that, in general, the ambient noise is a composite of at least three overlapping components: turbulent‐pressure fluctuations effective in the band 1 cps to 100 cps; wind‐dependent noise from bubbles and spray resulting, primarily, from surface agitation, 50 cps to 20 kc; and, in many areas, oceanic traffic, 10 cps to 1000 cps. Spectrum characteristics of each component and of the composite are shown. Additional sources, including those of intermittent and local effects, are also discussed. Guidelines for the estimation of noise levels are given.