Aria of the Dutch North Sea

  Underwater sound is a critical tool for aquatic animals that communicate acoustically or exploit environmental sounds to find prey,avoid predators,for orientation.The interference of various anthopogenic and natural sound sources can make it difficult to distinguish biologically relevant sounds and can even cause physical damage to these animals.This has given rise to international concern about possible effects of anthropogenic sound sources on marine life due to increasing shipping traffic,exploitation of oil and gas reserves and the development of new offshore energy sources.In this thesis, the spatial, temporal and spectral distributions of sound generated by anthropogenic and natural sources in the Dutch North Sea are investigated. In order to achieve this aim, the acoustic propagation algorithms are developed;compared with other propagation methods;source characteristics are modelled;and the resulting sound distribution is mapped for each source type.The acoustic insights and mathematical tool box that came out should help policy makers, legislators, biologists and conservationists and may serve in ecological monitoring and impact assessments, guide marine research efforts and may be used to determine potential regions or periods of acoustic conflict between human activities and aquatic life.  IBL - OU

Harbour porpoise movement strategy affects cumulative number of animals acoustically exposed to underwater explosions

Anthropogenic sound in the marine environment can have negative consequences for marine fauna. Since most sound sources are intermittent or continuous, estimating how many individuals are exposed over time remains challenging, as this depends on the animals' mobility. Here we explored how animal movement influences how many, and how often, animals are impacted by sound. In a dedicated study, we estimated how different movement strategies affect the number of individual harbour porpoises Phocoena phocoena receiving temporary or permanent hearing loss due to underwater detonations of recovered explosives (mostly WWII aerial bombs). Geo-statistical distribution models were fitted to data from 4 marine mammal aerial surveys and used to simulate the distribution and movement of porpoises. Based on derived dose-response thresholds for temporary (TTS) or permanent threshold shifts (PTS), we estimated the number of animals affected in a single year. When individuals were free-roaming, an estimated 1200 and 24 000 unique individuals would suffer PTS and TTS, respectively. This equates to respectively 0.50 and 10% of the estimated North Sea population. In contrast, when porpoises remained in a local area, fewer animals would receive PTS and TTS (1100 [0.47%] and 15 000 [6.5%], respectively), but more individuals would be subjected to repeated exposures. Because most anthropogenic sound-producing activities operate continuously or intermittently, snapshot distribution estimates alone tend to underestimate the number of individuals exposed, particularly for mobile species. Hence, an understanding of animal movement is needed to estimate the impact of underwater sound or other human disturbance. © The authors 2016

Validated shipping noise maps of the Northeast Atlantic

Underwater noise pollution from shipping is globally pervasive and has a range of adverse impacts on species which depend on sound, including marine mammals, sea turtles, fish, and many invertebrates. International bodies including United Nations agencies, the Arctic Council, and the European Union are beginning to address the issue at the policy level, but better evidence is needed to map levels of underwater noise pollution and the potential benefits of management measures such as ship-quieting regulations. Crucially, corroboration of noise maps with field measurements is presently lacking, which undermines confidence in their application to policymaking. We construct a computational model of underwater noise levels in the Northeast Atlantic using Automatic Identification System (AIS) ship-tracking data, wind speed data, and other environmental parameters, and validate this model against field measurements at 4 sites in the North Sea. Overall, model predictions of the median sound level were within ±3 dB for 93% of the field measurements for one-third octave frequency bands in the range 125 Hz-5 kHz. Areas with median noise levels exceeding 120 dB re 1 μPa and 20 dB above modelled natural background sound were predicted to occur in the Dover Strait, the Norwegian trench, near to several major ports, and around offshore infrastructure sites in the North Sea. To our knowledge, this is the first study to quantitatively validate large-scale modelled noise maps with field measurements at multiple sites. Further validation will increase confidence in deeper waters and during winter months. Our results highlight areas where anthropogenic pressure from shipping noise is greatest and will inform the management of shipping noise in the Northeast Atlantic. The good agreement between measurements and model gives confidence that models of shipping noise can be used to inform future policy and management decisions to address shipping noise pollution

Chapter 19 Noise pollution and its impact on human health and the environment

This chapter deals with (1) the basic theory of sound propagation; (2) an overview of noise pollution problem in view of policy and standards by the World Health Organization, the United States, and the European Union; (3) noise exposure sources from aircraft, road traffic and railways, in-vehicle, work, and construction sites, and occupations, and households; (4) the noise pollution impact on human health and the biological environment; (5) modeling of regional noise-affected habitats in protected and unprotected land areas and the marine environment; (6) noise control measures and sustainability in view of sustainable building design, noise mapping, and control measures such as barriers and berms along roadsides, acoustic building materials, roadway vehicle noise source control, road surface, and pavement materials; and (7) environmental noise pollution management measures and their impact on human health

Aria of the Dutch North Sea

  Underwater sound is a critical tool for aquatic animals that communicate acoustically or exploit environmental sounds to find prey,avoid predators,for orientation.The interference of various anthopogenic and natural sound sources can make it difficult to distinguish biologically relevant sounds and can even cause physical damage to these animals.This has given rise to international concern about possible effects of anthropogenic sound sources on marine life due to increasing shipping traffic,exploitation of oil and gas reserves and the development of new offshore energy sources.In this thesis, the spatial, temporal and spectral distributions of sound generated by anthropogenic and natural sources in the Dutch North Sea are investigated. In order to achieve this aim, the acoustic propagation algorithms are developed;compared with other propagation methods;source characteristics are modelled;and the resulting sound distribution is mapped for each source type.The acoustic insights and mathematical tool box that came out should help policy makers, legislators, biologists and conservationists and may serve in ecological monitoring and impact assessments, guide marine research efforts and may be used to determine potential regions or periods of acoustic conflict between human activities and aquatic life.  </div

Hindcasting soundscapes before and during the covid-19 pandemic in selected areas of the north sea and the adriatic sea

The national measures in several European countries during the COVID-19 pandemic also affected offshore human activities, including shipping. In this work, the temporal and spatial variations of shipping sound are calculated for the years before and during the pandemic in selected shallow water test areas from the Southern North Sea and the Adriatic Sea. First, the monthly sound pressure level maps of ships and wind between 2017 and 2020 are calculated for frequencies between 100 Hz to 10 kHz. Next, the monthly changes in these maps are compared. The asymptotic approximation of the hybrid flux-mode propagation model reduces the computational requirements for sound mapping simulations and facilitates the production of a large number of sound maps for different months, depths, frequencies, and ship categories. After the strictest COVID-19 measures were applied in April 2020, the largest decline was observed for the fishing, passenger and recreational ships. Although the changes in the number of fishing vessels are large, their contribution to the soundscape is minor due to their low source level. In both test areas, the spatial exceedance levels and acoustic energies were decreased in 2020 compared to the average of the previous three years.Offshore Engineerin

A depth-dependent formula for shallow water propagation

In shallow water propagation, the sound field depends on the proximity of the receiver to the sea surface, the seabed, the source depth, and the complementary source depth. While normal mode theory can predict this depth dependence, it can be computationally intensive. In this work, an analytical solution is derived in terms of the Faddeeva function by converting a normal mode sum into an integral based on a hypothetical continuum of modes. For a Pekeris waveguide, this approach provides accurate depth dependent propagation results (especially for the surface decoupling) without requiring complex calculation methods for eigenvalues and corresponding eigenfunctions. © 2014 Acoustical Society of America

Insights into the Calculation of Metrics for Transient Sounds in Shallow Water

Concern about possible impact of human activity on marine life has led to regulation in the USA [1,2] and the EU [3].The EU’s Marine Strategy Framework Directive [3] requires member states to achieve Good Environmental Status (GES) by 2020. Descriptor 11 of GES is “Introduction of energy, including underwater noise, is at levels that do not adversely affect the marine environment”, for which two indicators are specified [4]. The effect of underwater sound on aquatic animals is a research topic in need of multidisciplinary effort between acousticians and biologists, in order to provide a quantitative description of the sound field and to understand the impact of the sound on aquatic life. Sound exposure level (SEL), sound pressure level (SPL) and peak pressure are widely used as metrics for assessing environmental impact [5, 6].This paper described the calculation of SEL and SPL for impulsive sounds in shallow water (relevant to Indicator 11.2.1 of GES Descriptor 11), with particular attention to the difficulties ass

Modeling and assessing the effects of the sea surface, from being flat to being rough and dynamic

The sea surface acts as a very strong reflector because of the large impedance contrast between water and air. The reflection coefficient is -1 in a very good approximation. Apart from the surface multiples, the sea surface is also responsible for generating the source and receiver ghost wavefields. These cause the well-known ghost notches in the spectrum: areas where the signal-to-noise ratio is very low. To model the ghost wavefields, ghost operators can be computed and applied to ghost-free data. Modeling experiments indicate that in the case of a flat sea surface, the character of the notches in various gather types, e.g., receiver gather, common-offset gather, shot record, is largely determined by the complexity of the earth. In a simple earth, e.g., horizontally layered, the notches are always well-defined and deep, but in a complex earth, they become blurry in some of the gather types. Therefore, in the case of a complex subsurface, source deghosting is best carried out in the common-receiver domain and receiver deghosting is best carried out in the common-shot domain. In the case of a simple subsurface, deghosting can be carried out in all domains. An additional factor is that the sea surface may be rough and dynamic. This causes blurry ghost notches in all gather types, even in the case of a simple earth. To model the source ghost for this situation, an effective static rough sea surface suffices. This keeps the computations simple. The condition is that the source has an impulsive character. However, to model the receiver ghost (and the source ghost for a nonimpulsive source), the dynamics of the sea surface must be included. This can be done by composing the final result from the results computed for several "frozen" snapshots of the dynamic sea surface.Accepted Author ManuscriptApplied Geophysics and Petrophysic

Source specific sound mapping: spatial, temporal and spectral distribution of sound in the Dutch North Sea

Animal science