GB/T 41311.1-2022 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

Scope

This document specifies the general measurement system, measurement steps, and measurement methods for underwater radiation noise measurement of ships under specified operating conditions. This document does not specify underwater noise limits or provide guidance for them, nor does it address the potential impact of underwater noise on marine life. The measurement results are given in terms of root-mean-square sound pressure level (SPL), so the sound pressure level or SPL measured in the far field underwater of ships can be used equivalently, and after being normalized to a distance of 1 m, the measurement results are given in terms of 1/3 octave bandwidth (see Section 4.3). In this document, these measurement results are referred to as "radiation noise levels". The sound pressure level is measured in the geometric far field and then normalized to a distance of 1 m for comparison with the corresponding underwater noise limits. This document is applicable to the measurement of underwater radiation noise from various manned or unmanned surface ships during navigation, but not to submarines or aircraft. There are no fixed restrictions on the size of the ships for the measurement methods, but the ship's navigation speed should not exceed 25.7 m/s (50 knots). The measurement methods smooth out the Lloyd's mirror interference effect, but do not eliminate the influence of propagation effects such as seabed reflection, seawater refraction, and absorption. For these effects, this document does not provide specific calculation corrections. This document does not require a fixed measurement location, but it does set specific requirements for the selection of measurement locations. The intended uses of the methods described in this document include: comparison with contractual limit requirements, comparison of similar ships, evaluation of line spectrum characteristics, and research and development. Potential users include government agencies, scientific research ship operators,

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