Sound energy flow-based active noise control for tonal sound fields in shallow-water acoustic channels

Low-frequency tonal noise in shallow-water channels exhibits strong energy concentration and weak propagation attenuation, which limits the effectiveness of conventional pressure-based active noise control methods. In this study, an acoustic-intensity-based multichannel adaptive active control approach is extended and adapted for shallow-water environments. An offline secondary-path estimation scheme is employed to optimize the spatial configuration of sensors and secondary sources, and a self-developed acoustic-intensity sensing unit is used to acquire sound field information. The secondary sound field is adaptively regulated to destructively interfere with the primary field under shallow-water waveguide conditions. Numerical simulations and sea trials conducted in the shallow-water environment of the Yellow Sea demonstrate effective noise reduction in the 20-200 Hz band, with a maximum far-field attenuation of 20 dB. Compared with conventional pressure-based control, the proposed implementation exhibits a wider effective control region and improved stability within the investigated frequency range. The results indicate that acoustic-intensity-based adaptive control is a practical and effective solution for low-frequency noise mitigation of underwater vehicles operating in shallow water.