Overview
The article discusses the issue of ocean ambient noise and its impact on marine mammals, maritime security, strategic missions, and the health of divers. Commercial shipping is identified as a major source of noise in the sea, with cavitation at the propeller as the dominating noise source. Several models are discussed for predicting shipping noise, including the Ross, RANDI, Wales-Heitmeyer, SONIC, and Wittekind models. Wind noise is also discussed, with an empirical model based on underwater sound recordings identified as the best option.
The article also covers the topic of transmission losses and compares different hydroacoustic models, including the ray model, normal model, fast field program model, and parabolic equation model. The importance of improved acoustic capability for the Indian Ocean Region is emphasized, and the potential benefits of 3D sound mapping and characterizing ambient noise in shallow water are discussed.
Key highlights
- Shipping noise is a major contributor to ocean ambient noise, and it has adverse effects on the marine environment.
- There are various models available to predict shipping noise, such as the Ross model, RANDI model, Wales-Heitmeyer model, SONIC model, and Wittekind model.
- Wind noise is another source of underwater noise, and an empirical model is available to predict it.
- Transmission losses decrease the acoustic intensity due to geometrical spreading, attenuation, and scattering as an underwater sound wave propagates outwards from a source.
- Different hydroacoustic models, such as the Empirical model, Ray model, Normal model, and parabolic equation model, have limitations in applicable situations.
- The study proposes mapping and characterizing ambient noise in shallow water to improve underwater domain awareness in the Indian Ocean region.
Key Challenges
- The main challenges in studying and modeling ocean noise include the need to account for specific ship specifications
- Ships are divided into classes which does include the individual identity. Like individual age, structure can affect noise. So, ship data can be more comprehensive.
- Boundary scattering is not dealt in PERAM model which can be dealt with.
- Inclusion of wind and may be precipitation if possible as precipitation noise also falls in our interest of frequency.
- Use of DBN in calculation of Transmission loss.
- There is a need for better acoustic capability to improve Underwater Domain Awareness (UDA) in the Indian Ocean Region (IOR).
Major Opportunities
- Developing advanced acoustic mapping and characterization technologies for better understanding of ambient noise in shallow waters.
- Creating effective noise reduction measures for the shipping industry to mitigate the adverse effects of shipping noise on the marine environment.
- Developing and implementing advanced hydroacoustic models for accurate prediction of underwater acoustic transmission losses in complex naval battles and underwater operations.
- Developing new technologies and approaches for monitoring and mitigating the impact of ambient noise on marine mammals and the health of divers.
"For improved Underwater Domain Awareness, the Indian Ocean Region (IOR) needs to have better acoustic capability (UDA)."
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