International Airgun Modeling Workshop: Validation of Source Signature and Sound Propagation Models - Dublin (Ireland), July 16, 2016 - Problem Description

Computer models can be used to predict the sound field near an airgun or airgun array. The accuracy of such predictions can be assessed either by a process of verification (comparison with alternative theoretical solution to the same computational problem) or by validation (comparison with measurement). A set of verification test problems is...

Predicting acoustic dose associated with marine mammal behavioural responses to sound as detected with fixed acoustic recorders and satellite tags

To understand the consequences of underwater noise exposure for cetaceans, there is a need for assessments of behavioural responses over increased spatial and temporal scales. Bottom-moored acoustic recorders and satellite tags provide such long-term and large spatial coverage of behaviour compared to short-duration acoustic-recording tags....

Modelling propagation of sound emitted by mini-airguns

A modelling approach is described in which time-domain underwater-acoustic source functions are generated using a model that predicts the motion of air-bubbles generated by mini-airguns operated at various pressures. These time-series are Fourier-transformed to produce frequency-domain descriptions of the source. These are combined with complex...

Underwater sound radiation from subsea factories

In the oil & gas industry there is a trend towards more subsea activities such as the processing of the Oil and Gas in so-called 'subsea factories'. Regulations aimed at managing the impact of underwater sound on marine life are being put in place by different nations. Many offshore operations require an assessment of the potential impact of...

Flat acoustic sources with frequency response correction based on feedback and feed-forward distributed control

This paper presents an acoustic source with a small thickness and high bending stiffness. The high bending stiffness is obtained with a sandwich structure in which the face of the sandwich structure internal to the source is perforated to increase the acoustic compliance, thereby leading to increased electroacoustic conversion efficiency....

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...

An efficient model for prediction of underwater noise due to pile driving at large ranges

Modelling the sound levels in the water column due to pile driving operations nearby and out to large distances from the pile is crucial in assessing the likely impact on marine life. Standard numerical techniques for modelling the sound radiation from mechanical structures such as the finite element (FE) and boundary element method are not well...

QUIESST, toward a better knowledge and understanding of how efficient noise barriers could actually be: Noise in the built environment

Since the early 80's, one models noise propagation, in the early 90's one started to standardize how to measure the intrinsic characteristics of manufactured noise barriers: in 1997, the EU funded ADRIENNE research ([1] and [2]) was a first step, but many problems still remained. Since years, all the noise propagation software are still modeling...

A numerical technique to design blast noise mitigation measures

Large weapons, such as armor, artillery or demolitions, create a high-energy blast wave. It has a low frequency content, typically between 15 and 125 Hz, and can propagate over large distances. As a result it is a relative important cause for annoyance. Mitigation measures need to be close to the source for best effectiveness, but due to the...

Evaluation of the interim measurement protocol for railway noise source description

The Dutch national calculation scheme for railway noise has been declared the default interim method for railway noise calculation by the EU, until the introduction of results from the Harmonoise project. It includes a measurement protocol for determining emission input data in the format suitable for the present calculation scheme. The...

Influence of turbulent grazing flow on the impedance of an opening

In this paper, the impedance of a rectangular opening submitted to a turbulent grazing flow is investigated experimentally. The opening is located in a flat plate where a turbulent boundary layer flow develops. The impedance is measured with a two-microphone measuring pipe installed below the opening. The opening has a rectangular shape of large...

On the assessment of shooting sounds: Loudness-level weightings versus A- and C-weighted sound exposure levels (L)

As an alternative to the A-weighted sound exposure level (ASEL) Schomer et al. [J. Acoust. Soc. Am. 110, 2390-2397 (2001)] used the equal-loudness level contours as a dynamic filter to determine the loudness-level-weighted sound exposure level (LLSEL). From their analyses they concluded that the LLSEL better orders and assesses traffic and...

Flow-induced noise around the a-pillar of an idealized car greenhouse

Due to the successes in reducing motor and tire noise as perceived inside cars and trucks, aerodynamically generated noise becomes more and more important. Some time ago the study of aero-acoustics in and around these vehicles was mainly done by wind tunnel test. Nowadays, computational methods become available that allow for numerical...

A European comparison of medical ultrasonic field measurements: Interpreting IEC 61157

A European comparison of measurements of medical ultrasonic fields at diagnostic levels has been carried out. The exercise, led by the United Kingdom's National Physical Laboratory (NPL), also aimed to assess the ability of participants to apply the measurement procedures set out in the specification standard IEC 61157:1992 entitled ...

Reduction of the performance of a noise screen due to screen-induced wind-speed gradients: Numerical computations and wind-tunnel experiments

Downwind sound propagation over a noise screen is investigated by numerical computations and scale model experiments in a wind tunnel. For the computations, the parabolic equation method is used, with a range-dependent sound-speed profile based on wind-speed profiles measured in the wind tunnel and wind-speed profiles computed with computational...