@article {58172, title = {Techniques for distinguishing between impulsive and non-impulsive sound in the context of regulating sound exposure for marine mammals}, journal = {The Journal of the Acoustical Society of America}, volume = {147}, year = {2020}, month = {Jan-04-2020}, pages = {2159 - 2176}, abstract = {

Regulations designed to mitigate the effects of man-made sounds on marine mammal hearing specify maximum daily sound exposure levels. The limits are lower for impulsive than non-impulsive sounds. The regulations do not indicate how to quantify impulsiveness; instead sounds are grouped by properties at the source. To address this gap, three metrics of impulsiveness (kurtosis, crest factor, and the Harris impulse factor) were compared using values from random noise and real-world ocean sounds. Kurtosis is recommended for quantifying impulsiveness. Kurtosis greater than 40 indicates a sound is fully impulsive. Only sounds above the effective quiet threshold (EQT) are considered intense enough to accumulate over time and cause hearing injury. A functional definition for EQT is proposed: the auditory frequency-weighted sound pressure level (SPL) that could accumulate to cause temporary threshold shift from non-impulsive sound as described in Southall, Finneran, Reichmuth, Nachtigall, Ketten, Bowles, Ellison, Nowacek, and Tyack [(2019). Aquat. Mamm. 45, 125\–232]. It is known that impulsive sounds change to non-impulsive as these sounds propagate. This paper shows that this is not relevant for assessing hearing injury because sounds retain impulsive character when SPLs are above EQT. Sounds from vessels are normally considered non-impulsive; however, 66\% of vessels analyzed were impulsive when weighted for very-high frequency mammal hearing.

}, issn = {0001-4966}, doi = {10.1121/10.0000971}, url = {http://asa.scitation.org/doi/10.1121/10.0000971}, author = {Martin, S. Bruce and Lucke, Klaus and Barclay, David R.} } @article {53410, title = {An Empirical Mode Decomposition-based detection and classification approach for marine mammal vocal signals}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-12-2018}, pages = {3181 - 3190}, abstract = {

Detecting marine mammal vocalizations in underwater acoustic environments and classifying them to species level is typically an arduous manual analysis task for skilled bioacousticians. In recent years, machine learning and other automated algorithms have been explored for quickly detecting and classifying all sound sources in an ambient acoustic environment, but many of these still require a large training dataset compiled through time-intensive manual pre-processing. Here, an application of the signal decomposition technique Empirical Mode Decomposition (EMD) is pre- sented, which does not require a priori knowledge and quickly detects all sound sources in a given recording. The EMD detection process extracts the possible signals in a dataset for minimal quality control post-processing before moving onto the second phase: the EMD classification process. The EMD classification process uniquely identifies and labels most sound sources in a given environ- ment. Thirty-five recordings containing different marine mammal species and mooring hardware noises were tested with the new EMD detection and classification processes. Ultimately, these pro- cesses can be applied to acoustic index development and refinement.

}, issn = {0001-4966}, doi = {10.1121/1.5067389}, url = {http://asa.scitation.org/doi/10.1121/1.5067389}, author = {Seger, Kerri D. and Al-Badrawi, Mahdi H. and Kirsch, Nicholas J. and Lyons, Anthony P.} } @article {53327, title = {Source localization using a compact tetrahedral array}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-09-2018}, pages = {1745 - 1745}, abstract = {

We localized sound sources collected on a compact tetrahedral hydrophone array in a continental shelf environment south of Block Island, Rhode Island. The tetrahedral array of phones, 0.5 m on a side, was deployed to monitor the underwater sound of construction and operation of the first offshore wind farm in the United States. Signals from shipping and marine mammals, including fin whales, humpback whales, and right whales, were detected on the array. Directions of arrival (DOAs) for a number of signals were computed using a time difference of arrival technique. Given the DOAs, ranges were estimated using supervised machine learning techniques outlined by Niu et al. (JASA, 2017). The approach was tested using simulated data from Kraken assuming environmental information consistent with this continental shelf environment. Performance on signals from individual ships and marine mammals is presented. Ship localizations are compared to Automated Identification System (AIS) fixes. An error analysis is also presented. [Work supported by the Office of Naval Research and the Bureau of Ocean Energy Management.]

}, issn = {0001-4966}, doi = {10.1121/1.5067739}, url = {http://asa.scitation.org/doi/10.1121/1.5067739}, author = {Potty, Gopu R. and Tripathy, Aditi and Tazawa, Makio and Amaral, Jennifer and Vigness-Raposa, Kathleen J. and Lin, Ying-Tsong and Newhall, Arthur} } @article {53315, title = {Relationship between cetacean presence, their prey, and oceanographic conditions at an offshore pelagic environment}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-09-2018}, pages = {1921 - 1921}, abstract = {

Large mobile predators take advantage of offshore pelagic environments that tend to be surveyed at a low temporal scale. We present results from a one-year observation of passive and active acoustics, as well as oceanographic measures, taken at a moored location 150 nmi offshore southern California in 4000 m deep pelagic waters. The passive acoustic data shows presence of delphinids and baleen, sperm, and beaked whales throughout the recording period with species-specific seasonal occurrence. Variability in small pelagics, krill, and diel vertical migrators is evident from the active acoustic data. Multiple upwelling events and associated changes in dissolved oxygen at 500 m water depth, as well as in surface waters, were also recorded over the year. We will present results on the relationships among oceanographic variability, presence of pelagic species, and top predator presence. This study will provide valuable information on ecosystem processes in meso- and epipelagic waters on a relatively small spatial scale but very fine temporal scale.

}, issn = {0001-4966}, doi = {10.1121/1.5068413}, url = {http://asa.scitation.org/doi/10.1121/1.5068413}, author = {Baumann-Pickering, Simone and Trickey, Jennifer S. and Rice, Ally and {\v S}irovi{\'c}, Ana and Renfree, Josiah and Demer, David A.} } @article {53304, title = {Vertical line array tilt revealed through snapping shrimp noise}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-09-2018}, pages = {1921 - 1921}, abstract = {

The shallow-water acoustic variability experiment (SAVEX15), conducted in the East China Sea, unexpectedly recorded a great deal of snapping shrimp noise on a 16-element (56-m length) vertical line array deployed in 100-m water depths. These impulsive events can be used to find the tilt of the moored array which was caused by the strong ocean currents in the area. In this environment, the recorded snaps of bottom-dwelling shrimp within a radius of more than 500 m were largely separated from one another in time, and coherent time domain beamforming was successful in localizing snaps in time and range. The sparse and impulse nature of the snaps allowed for a simple normalization and gave tens of snap detections per second after a threshold detector. The results from the automated detector showed it was necessary to search with the beamformer over a three-dimensional space for reliable performance: (1) arrival time, (2) source range, and (3) array tilt. The results of the beamformer search in array tilt space are consistent with independent acoustic tilt measurements of the same array, showing that snapping shrimp noise in this region can provide valuable inference for the acoustic environment.

}, issn = {0001-4966}, doi = {10.1121/1.5068412}, url = {http://asa.scitation.org/doi/10.1121/1.5068412}, author = {Richards, Edward and Yuan, Zhuqing and Song, Hee-Chun and Hodgkiss, William S.} } @article {53296, title = {Predator-prey interactions in the Southern California Bight}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-09-2018}, pages = {1921 - 1921}, abstract = {

The Southern California Bight (SCB) is an important foraging area for a variety of cetacean species, including blue whales and beaked whales. However, the interactions of these species with their prey (krill and deep-water squid, respectively) can be very difficult to observe. Moorings combining passive and active acoustics were deployed at two locations in the SCB in two consecutive fall and winter seasons. A High-frequency Acoustic Recording Package sampling at 200 kHz recorded the full range of baleen and beaked whale signals. The active acoustic system on each mooring included two Simrad Wide Band Acoustic Transceivers (WBAT). A bottom-mounted WBAT had an upward looking 70 kHz transducer and the one at 300 m depth had upward looking 70 kHz and 200 kHz transducers. Over the course of four months, blue whale songs and social calls were recorded on both moorings. Beaked whale echolocation clicks were commonly detected on the mooring deployed offshore, with only rare beaked whale encounters on the coastal mooring. Backscatter data indicated overlap in the presence of cetacean predators and their prey. Scattering layer dynamics were dominated by regular diel migration, with differences in scatterer abundance between mooring sites, as well as on 2\–5 day time scales.

}, issn = {0001-4966}, doi = {10.1121/1.5068414}, url = {http://asa.scitation.org/doi/10.1121/1.5068414}, author = {{\v S}irovi{\'c}, Ana and Baumann-Pickering, Simone and Warren, Joseph} } @article {53282, title = {Spatio-temporal modelling of underwater noise related to an arctic exploration drilling program}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-09-2018}, pages = {1733 - 1733}, abstract = {

One concern related to oil and gas industry activities in the arctic is the potential impact of anthropogenic noise on marine mammals. To gain understanding of the temporal evolution of the acoustic noise footprint from such activities, and to quantify the geographic extent at which sound levels remain within regulatory thresholds for marine mammal injury and behavioral disturbance, this work presents a comprehensive monitoring and modeling study of anthropogenic noise resulting from an exploration drilling project in the northeastern Chukchi Sea, conducted from July to October, 2015. Measured acoustic source levels of multiple vessels and drilling equipment were used to generate time-dependent wide-area noise fields. Model validation was carried out by comparing simulated results with high-resolution acoustic data acquired at multiple stations in the area. The study shows that noise radiating from up to 19 supporting vessels is usually dominant, but noise from certain drilling-related activities occasionally rises above vessel noise within a radius of 8 km from drillsites. Modeled scenarios also show that by constraining vessel positions to within a few kilometers of the drilling location, simultaneous construction of two oil well top holes results in minor increment of the aggregate acoustic footprint\’s extent relative to single-well drilling.

}, issn = {0001-4966}, doi = {10.1121/1.5067686}, url = {http://asa.scitation.org/doi/10.1121/1.5067686}, author = {Quijano, Jorge E. and Hannay, David E. and Melanie E. Austin} } @article {53277, title = {The feasibility of a multipurpose acoustic network in Baffin Bay}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-09-2018}, pages = {1984 - 1984}, abstract = {

Operating autonomous underwater vehicles at high latitudes is a challenge because ice cover prevents the use of GPS or data communications. As a result, our scientific observations are biased towards late spring, summer, and early autumn when ships can navigate and autonomous platforms can safely surface. To address this problem, we studied the feasibility of a basin-scale multipurpose acoustic network called the \“Baffin Bay Acoustic Navigation and Communication System\” (BBANC). BBANC would deploy broadband low frequency sources and receivers, offering one-way communication, acoustic positioning, and acoustic thermometry services. Passive acoustic listening elements would support the study of marine mammal communication and ambient noise from ships, ocean-based resource exploitation, and ice dynamics, as well as gate acoustic source operation in the presence of marine mammals. We describe the challenges and design parameters for such a system, as well as define additional acoustic and remote sensing measurements required to complete a system design. Drawing from a large database of Baffin Bay hydrography, we present simulations of under-ice sound speed conditions, ice properties derived from satellite remote sensing and upward looking sonar data, and modelled acoustic propagation paths in an ice-covered Baffin Bay. We also assess the feasibility of non-coherent and coherent communication.

}, issn = {0001-4966}, doi = {10.1121/1.5068660}, url = {http://asa.scitation.org/doi/10.1121/1.5068660}, author = {Rehm, Eric and Dushaw, Brian D. and Freitag, Lee E. and Heaney, Kevin D. and Carr, Scott and Dakin, Thomas and Fissel, David and Heard, Garry J.} } @article {53270, title = {Multi-year measurements of the underwater noise field directionality in the shallow Beaufort Sea during open-water and drifting ice flow conditions}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-09-2018}, pages = {1696 - 1697}, abstract = {

Between 2007 and 2014, over 35 Directional Autonomous Seafloor Acoustic Recorders (DASARs) were deployed over a 280 km swath of the Beaufort Sea continental shelf (20\–55 m depth) during the open-water season, in order to monitor the fall (westward) bowhead whale migration. DASARs have one omnidirectional pressure sensor and two orthogonal particle motion sensors, which permit instantaneous measurements of the azimuths of both transient signals and continuous noise between 20 and 500 Hz. The lack of significant shipping or industrial noise in this region provided a rare opportunity to directly measure the properties of wind-driven noise in expanding ice-free regions. Here, we map the azimuthal directionality of the diffuse Beaufort ambient noise field as a function of frequency and space across seven seasons. The dominant directionality of the diffuse ambient noise field varied strongly with frequency and was highly correlated with the received power spectral density. Certain directional features of the ambient noise field remained stable over seven deployment seasons, suggesting that judicious processing of the ambient noise soundscape could provide underwater navigational information in arctic waters. The influence of local drifting floes and sheets of ice on this directionality is also examined. [Work sponsored by ONR.]

}, issn = {0001-4966}, doi = {10.1121/1.5067541}, url = {http://asa.scitation.org/doi/10.1121/1.5067541}, author = {Thode, Aaron and Blackwell, Susanna B. and Kim, Katherine H. and Alexander S. Conrad} } @article {53025, title = {Acoustic characterization of exploration drilling in the Chukchi and Beaufort seas}, journal = {The Journal of the Acoustical Society of America}, volume = {144}, year = {2018}, month = {Jan-07-2018}, pages = {115 - 123}, abstract = {

This paper characterizes underwater sound levels produced by three drilling units during offshore exploration drilling at three sites in the Beaufort and Chukchi seas. Received levels and spectra are reported as functions of distance during drilling and excavation of mudline cellars (MLCs). Sound levels emitted during MLC excavation exceeded those during drilling at all three sites, although this operation was much shorter in duration. Drilling sounds exhibited tones below 2\ kHz, with harmonics present to 10\ kHz, while MLC excavation sounds were broadband in character. Drilling sounds varied substantially between the three operations, whereas MLC excavation sounds were more consistent in amplitude and spectral distribution. Estimates of broadband and 1/3-octave band source levels were computed from measurements at 1\ km range. The broadband drilling source levels were 168.6\ dB re 1\ \μPa m for the Kulluk drilling unit, 174.9\ dB re 1\ \μPa m for the drillship Noble Discoverer, and 170.1\ dB re 1\ \μPa m for the semi-submersible Polar Pioneer. The received levels measured at 1\ km during MLC excavation yielded source level estimates that were more consistent among sources: 191.8, 193.0, and 193.3\ dB re 1\ \μPa for the Discoverer, Kulluk, and Polar Pioneer, respectively.

}, issn = {0001-4966}, doi = {10.1121/1.5044417}, url = {http://asa.scitation.org/doi/10.1121/1.5044417}, author = {Hannay, David E. and Br{\"o}ker, Koen C.} } @article {47789, title = {Habitat-dependent ambient noise: Consistent spectral profiles in two African forest types}, journal = {The Journal of the Acoustical Society of America}, volume = {116}, year = {2004}, month = {Jan-12-2004}, pages = {3727 - 3733}, abstract = {

Many animal species use acoustic signals to attract mates, to defend territories, or to convey information that may contribute to their fitness in other ways. However, the natural environment is usually filled with competing sounds. Therefore, if ambient noise conditions are relatively constant, acoustic interference can drive evolutionary changes in animal signals. Furthermore, masking noise may cause acoustic divergence between populations of the same species if noise conditions differ consistently among habitats. In this study, ambient noise was sampled in a replicate set of sites in two habitat types in Cameroon: contiguous rainforest and ecotone forest patches north of the rainforest. The noise characteristics of the two forest types show significant and consistent differences. Multiple samples taken at two rainforest sites in different seasons vary little and remain distinct from those in ecotone forest. The rainforest recordings show many distinctive frequency bands, with a general increase in amplitude from low to high frequencies. Ecotone forest only shows a distinctive high-frequency band at some parts of the day. Habitat-dependent abiotic and biotic sound sources and to some extent habitat-dependent sound transmission are the likely causes of these habitat-dependent noise spectra.

}, issn = {0001-4966}, doi = {10.1121/1.1811121}, url = {http://asa.scitation.org/doi/10.1121/1.1811121}, author = {Slabbekoorn, Hans} }