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.
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