ISO/TC 43/SC 3 - Underwater acoustics

ISO 17208 series describe procedures for the measurement of underwater sound radiated by the ship under test, and for calculating sound source quantities such as source level and radiated noise level from the measurement results. In ISO 17208-1 to ISO 17208-3 it is presumed that the ship under test cooperates in the measurements, sailing multiple runs over a specified track past the measurement system at a specified speed with pre-determined machinery configurations. Opportunistic measurements of the radiated sound of passing ships are outside the scope of these three standards. Part 1 of the ISO 17208 standards[ REF Reference_ref_4 \r \h 1 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000100000005200650066006500720065006E00630065005F007200650066005F0034000000 ] provides the procedure to quantify the underwater sound from the ship in terms of its radiated noise level, which is calculated from the sound pressure level (SPL) measured in the far field of the ship, in beam aspect, scaled by the distance to CPA and reported in decidecade bands. The intended use of radiated noise level is to show compliance with contract requirements or criteria, for comparison of one ship to another ship, to enable periodic signature assessments, and for research and development. ISO 17208-2[ REF Reference_ref_4 \r \h 1 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000100000005200650066006500720065006E00630065005F007200650066005F0034000000 ] specifies methods for calculating the source level of an equivalent monopole source at a specified nominal source depth from the radiated noise level values obtained according to ISO 17208-1. The intended use of source level, with associated nominal source depth, is to perform far field sound predictions such as needed for environmental impact studies or for creating underwater sound contour maps. ISO 17208-1 and ISO 17208-2[ REF Reference_ref_4 \r \h 1 08D0C9EA79F9BACE118C8200AA004BA90B0200000008000000100000005200650066006500720065006E00630065005F007200650066005F0034000000 ] are applicable for measurements in deep water, defined as water depth greater than the larger of 150 m and 1,5 times overall ship length. The allowable water depths and environmental conditions for part 3 measurements are described in REF Section_sec_4.5 \r \h 4.5 08D0C9EA79F9BACE118C8200AA004BA90B020000000800000010000000530065006300740069006F006E005F007300650063005F0034002E0035000000 . This document specifies procedures for the measurement of underwater sound radiated by the ship under test in shallow water. It also specifies procedures for the calculation of source level, with associated nominal source depth, from the sound pressure measurements, accounting for the relevant phenomena that govern the propagation of sound in shallow water. These calculations are described in REF Section_sec_7 \r \h Clause 7 08D0C9EA79F9BACE118C8200AA004BA90B02000000080000000E000000530065006300740069006F006E005F007300650063005F0037000000 . Once the source level has been calculated, other metrics may be calculated from the source level and the source depth. REF Section_sec_7.3 \r \h 7.3 08D0C9EA79F9BACE118C8200AA004BA90B020000000800000010000000530065006300740069006F006E005F007300650063005F0037002E0033000000 provides a procedure for calculating the radiated noise level that would have been measured in deep water according to ISO 17208-1 for the same ship with the same operating condition.

This document provides requirements and recommendations for measuring and reporting ambient sound in water, as characterized by sound pressure and selected quantities that can be derived from sound pressure. “Ambient sound” implies sound from any source except sources of self-noise. The scope includes equipment performance, calibration and deployment, digital data acquisition and data processing. Data processing is the process of converting raw data into a form and context necessary to be interpreted by people and computers. The scope includes data analysis and reporting of recordings of duration one day or longer. Five data processing stages are considered: raw digital acquisition data3), sound pressure time series, sound pressure level time series, sound pressure spectra and their statistics. The scope excludes measurement of particle motion. 3)The word data is generally used as a collective noun in this document; the plural form is reserved for cases where the constructive relationship to individual observations or measurements is to be emphasized.

This document specifies two procedures for the in situ determination of the insertion loss of underwater noise abatement measures (noise abatement systems). The impulsive sound of pile driving is used as the sound source for the investigation of noise abatement systems. This document does not apply to artificial sound sources and investigations under laboratory conditions. Apart from the correct application of the respective noise abatement system, the achieved sound attenuation also depends on the installation conditions (e.g. type of hammer, driving energy, pile dimensioning) as well as on the environmental conditions (e.g. water depth, seafloor classification and bathymetry, current and wind conditions) and the flanking transmission via the seafloor.

This document specifies methods for calculating an equivalent monopole source level by converting radiated noise level values obtained in deep water according to ISO 17208-1. Procedures are also given for direct calculation from measurements made in deep water with specific hydrophone geometry. The source level calculated by the procedure in this document is that of an equivalent monopole source at a specified nominal source depth, and for broadside aspect only. The nominal source depth is intended to be reported with the equivalent monopole broadside source level value.

ISO 18407:2017 describes the methodologies, procedures, and measurement systems to be used for the measurement of the radiated underwater acoustic sound generated during pile driving using percussive blows with a hammer. A major motivation for undertaking measurements of the sound radiated during percussive pile driving is as part of an assessment of impact on aquatic fauna required by regulatory frameworks. This document describes a generic approach to measurements that can be applied to different regulatory requirements. ISO 18407:2017 is suitable for measurement of percussive pile driving undertaken for offshore installation of foundations (monopiles, jackets, tripods, etc.) used in construction of offshore wind farms, oil and gas platforms, and other inshore structures such as bridge foundations and aquatic renewable energy devices. This document does not cover measurement of the sound radiated by vibro-piling or sheet piling. This document does not cover piling in water of depth less than 4 m or greater than 100 m. The procedures described herein provide guidance on making measurements to satisfy the following objectives: - to monitor source output during piling, for example, for regulatory purposes; - to provide consistency in comparison of piling noise from different construction projects; - for validation of modelling or predictions. ISO 18407:2017 covers only the measurement of the sound field radiated during percussive pile driving. The scope of this document does not include the assessment of exposure metrics, or the use of exposure criteria. No attempt is made to prescribe a methodology for generating maps of the acoustic field in the vicinity of the source. In the normative part of this document, requirements and procedures are described for measurement of the sound field at specific ranges from the pile being driven. In this part of the document, no procedure is provided for determination of an acoustic output metric that is independent of the propagation path between source and receiver (such as a source level). Ideally, such a metric would have some predictive utility (for example, in calculating noise impact zones and noise maps). However, some information on the determination of a possible acoustic output metric is provided in Annex A. ISO 18407:2017 covers only the measurement of sound pressure in the water column. The scope does not include measurement of sound particle velocity in the water column due to the propagating sound wave, or seabed vibration caused by waves propagating across the sea-floor. This exclusion does not imply that such measures are unimportant; indeed, their importance in assessing the impact on aquatic life is recognized. However, at the time of drafting, measurement of these quantities is not yet mature enough for standardization.

ISO 18405:2017 defines terms and expressions used in the field of underwater acoustics, including natural, biological and anthropogenic (i.e. man-made) sound. It includes the generation, propagation and reception of underwater sound and its scattering, including reflection, in the underwater environment including the seabed (or sea bottom), sea surface and biological organisms. It also includes all aspects of the effects of underwater sound on the underwater environment, humans and aquatic life. The properties of underwater acoustical systems are excluded.

ISO 17208-1:2016 specifies the general measurement system, procedure, and methodology used for the measurement of underwater sound from ships under a prescribed operating condition. It does not specify or provide guidance on underwater noise criteria or address the potential effects of noise on marine organisms. The resulting quantities are based on the root-mean-square sound pressure levels (SPL), herein used synonymously with sound pressure level or SPL measured in the far field of the ship and normalized to a distance of 1 m and reported in one-third octave bands (see 4.3). In this part of ISO 17208, the result of these measurements is called "radiated noise level". The underwater sound pressure level measurement is performed in the geometric far field and then adjusted to the 1 m normalized distance for use in comparison with appropriate underwater noise criteria. ISO 17208-1:2016 is applicable to any and all underway surface vessels, either manned or unmanned. It is not applicable to submerged vessels or to aircraft. The method has no inherent limitation on minimum or maximum ship size. It is limited to ships transiting at speeds no greater than 50 kn (25,7 m/s). The measurement method smooths the variability caused by Lloyd's mirror surface image coherence effects, but does not exclude a possible influence of propagation effects like bottom reflections, refraction and absorption. No specific computational adjustments for these effects are provided in this part of ISO 17208. A specific ocean location is not required to use this part of ISO 17208, but the requirements for an ocean test site are provided. The intended uses of the method described in this part of ISO 17208 are: to show compliance with contract requirements or criteria, for comparison of one ship to another ship, to enable periodic signature assessments, and for research and development. The intended users include government agencies, research vessel operators, and commercial ship owners. Additional post-processing would be required to use the data obtained from this measurement method for determination of the ship source levels to perform far field noise predictions such as needed for most environmental impact studies or for creating underwater noise contour maps.

ISO/PAS 17208-1:2012 describes the general measurement systems, procedures and methodologies to be used to measure underwater sound pressure levels from ships at a prescribed operating condition. It presents a methodology for the reporting of one-third-octave band sound pressure levels. The resulting quantities are the sound pressure levels normalized to a distance of 1 m. The underwater sound pressure level measurements are performed in the geometric far field and then adjusted to the 1 m normalized distance for use in comparison with appropriate underwater noise criteria. ISO/PAS 17208-1:2012 does not specify or provide guidance on underwater noise criteria or address the potential effects of noise on marine organisms. It is applicable to any and all underway surface vessels, either manned or unmanned. Its methods have no inherent limitation on minimum or maximum vessel size. It is not applicable to submerged vessels or to aircraft, and is limited to vessels transiting at speeds no greater than 50 knots (25,70 m/s). The measurement methods mitigate the variability caused by Lloyd's mirror surface image coherence effects, but do not exclude a possible influence of propagation effects such as bottom reflections, refraction and absorption. No specific computational adjustments for these effects are given. A specific ocean location is not required for the application of ISO/PAS 17208-1:2012, but requirements for an ocean test site are provided. Among the applications of ISO/PAS 17208-1:2012 are the showing of compliance with contract requirements, the enabling of periodic signature assessments and in research and development. Intended users include government agencies, research vessel operators and commercial vessel owners operating in acoustically sensitive waters.