ObjectivesAn underwater anechoic coating layer laid on the hull surface of a submarine is squeezed under the action of high hydrostatic pressure, changing its shape and material parameters, which has a great impact on sound absorption performance. Therefore, studying the sound absorption performance of underwater anechoic coating layers under high hydrostatic pressure is of great significance for the stealth performance of submarines.MethodsConsidering the effects of cavity pressure on deformation and sound absorption performance of the annechoic coating layer under hydrostatic pressure, this paper uses axisymmetric finite element simulation to calculate the deformation of single cell with a cylindrical cavity, and the sound absorption coefficient curve is then obtained by converting the deformations into one-dimensional theoretical model. After that, structural-acoustic coupling analysis with the geometric model after deformation is carried out to verify the effectiveness of theorectical and numerical approaches for soloving the sound absorption coefficient.ResultsThe results indicate that, without considering the changes of material parameters, the unit cells of the layer shrink axially and the cavity shrinks radially under hydrostatic pressure, while the sound absorption curve moves towards high frequency. The air pressure inside the cavity resists contraction under the action of hydrostatic pressure, weakening the trend of moving to high frequency. The sharp valley in the sound absorption curve is caused by the excitation of cavity mode.ConclusionsThe results of this study can provide valuable references for predicting the sound absorption performance of an anechoic coating layer under hydrostatic pressure.