A systematic review on mechanism and regulation strategy of marine hydrodynamic noise: Advances, challenges, and perspectives

Abstract

Noise pollution in the oceans has emerged as a significant environmental concern, garnering increasing global attention in recent years. It will harm human health and the survival of species and weaken equipment reliability. With advancements in navigation technology and marine resource exploitation, issues of hydrodynamic noise are expected to rise increasingly, which poses a significant challenge to marine noise management. Therefore, there is a necessity to explore new technologies to improve marine acoustic environments. This review first summarizes and analyzes the existence scenarios and generation mechanisms of hydrodynamic noise near or far off the coast. Then, the mitigation principles and applications of passive noise control (PNC), active noise control (ANC), and active-passive hybrid noise control (HNC) techniques for hydrodynamic noise control (Hydro-NC) are discussed, as well as their recent advancements. An overview of physical materials and particular structures used in PNC is followed, which either modulate the noise intensity/source by altering the flow field or directly absorb the sound at the source/transmission path to reduce the total noise levels at a specified frequency band. In addition, ANC is pioneeringly introduced to regulate hydrodynamic noise in the oceans; its mitigation mechanism, latest progress, and future perspectives for Hydro-NC are explored. To guarantee more critical acoustic requirements, it further discusses the coupling strategies of PNC and ANC and proposes some novel conceptual HNC, as well as their potential on Hydro-NC. Finally, challenges and future perspectives of PNC, ANC, and HNC in Hydro-NC are presented.