Bubble curtain

The technique is based on bubbles of air (gas) being let out under the water surface, commonly on the bottom.

When the bubbles rise they act as a barrier, a curtain, breaking the propagation of waves or the spreading of particles and other contaminants.

When used to reduce acoustic waves from pile driving, a distribution manifold made of plastic or rubber is commonly used.

[10] Pile driving in connection to offshore construction, most importantly monopile foundations for offshore wind turbines, produces very high levels of underwater noise,[3] capable of inflicting damage to the hearing of marine organisms[11] and deter animals at tens of km from the construction site.

[12][13] Large-scale bubble curtains are now routinely used to mitigate these impacts as they can attenuate the noise significantly, in particular the higher frequencies, above 1 kHz.