ISO has developed a new international standard to measure the underwater noise from ships.
Excessive underwater noise has the potential to interfere with a marine animal’s ability to perform a variety of critical life functions, including navigation, communication and finding food. Because of this, the environmental impact statements of underwater projects such as pile driving, pipe laying and oil exploration now include assessments of underwater noise impact.
Hence, ISO has established new international standard for gauging the underwater noise from ships in the classification ISO 17208-1:2016, wholly named as “Underwater acoustics- Quantities and procedures for description and measurement of underwater sound from ships- Part 1: Requirements for precision measurements in deep water used for comparison purposes”.
The standard specifies the measurement system in general, procedures and methodology in use for the measurement of underwater sound from ships, in a prescribed operating condition.
Where is this ISO standard applicable?
This 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).
How does this work?
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. 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.
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.
Uses & its Users:
- 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.
Development of the Standard:
A leader in the field of shipboard noise control, Noise Control Engineering, LLC (NCE) has taken efforts to develop this standard. “This is very similar to the American National Standard ANSI/ASAS12.64/1, developed in 2009, but with many improvements, most importantly the removal of the three grades”, noted Michael Bahtiarian, the working group chair.
The Acoustical Society of America’s standards Manager, Susan Blaeser, served as Secretary of ISO/TC 43/SC 3 which developed the new standard. She was acute companion in moving the original ANSI/ASA S12.64 into the international arena.
Ms. Blaeser notes, “It was very satisfying to bring our American National Standard to the international underwater acoustics community. The new standard is the result of international collaboration between experts representing at least twelve countries.”
Source: ISO
