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Measuring vessel source level in shallow water using the smoothed semi-coherent image method

  • 0TSI, Madrid, Spain.
The Journal of the Acoustical Society of America +

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March 21, 2025

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March 21, 2025

View abstract on PubMed

Summary

This summary is machine-generated.

A new method for measuring ship underwater radiated noise (URN) in shallow waters improves accuracy. The smoothed semi-coherent image (SSCI) method offers a more reliable way to calculate source levels (SL) compared to existing standards.

Area Of Science

  • Acoustics
  • Oceanography
  • Marine Engineering

Background

  • Standardizing measurements of underwater sound from ships in shallow waters is challenging.
  • Current methods, like the seabed critical angle (SCA) method (ISO 17208-3 draft), may underestimate source levels (SL) above 500 Hz.
  • Accurate source level derivation from sound pressure level (SPL) measurements requires precise propagation loss (PL) approximations.

Purpose Of The Study

  • To present and evaluate an alternative method, the smoothed semi-coherent image (SSCI) method, for calculating propagation loss (PL) and source levels (SL) in shallow waters.
  • To assess the performance of the SSCI method against analytical and empirical data.
  • To offer a more accurate and robust approach for underwater radiated noise (URN) measurements.

Main Methods

  • Developed the smoothed semi-coherent image (SSCI) method for calculating underwater propagation loss (PL).
  • Evaluated the SSCI method using analytical scenarios and empirical data from the SATURN project.
  • Conducted URN tests with multiple instrumentation deployment strategies, depths, and distances.

Main Results

  • The SSCI method demonstrated enhanced accuracy in calculating source levels (SL) across a broad frequency range compared to the SCA method.
  • The SCA method showed a general underestimation of SL above approximately 500 Hz.
  • The SSCI method maintains robustness and seeks to preserve the simplicity of the SCA approach.

Conclusions

  • The SSCI method provides a more accurate and reliable approach for determining ship source levels (SL) in shallow waters.
  • This method addresses the limitations of existing standards like ISO 17208-3 for shallow water URN measurements.
  • The SSCI method offers a promising alternative for standardizing shallow water acoustic measurements.