Sound absorption of periodically cavities with gradient changes of radii and distances between cavities in a soft elastic medium

Abstract An acoustic model comprising periodic cylindrical cavities embedded in a soft elastic medium with gradient changes of radii and distances is presented. The main advantage of this model is that high sound absorption across a broadband frequency range can be realized. The basic mechanism for sound absorption is based on Fabry–Perot resonance. A numerical model using the finite element method is developed to study the sound absorption performance of the model for different cases. Results from the numerical model are validated with those obtained using an analytical model from literature. Simulation results show that the sound absorption is sensitive to the gradient profile of radii and distances between cavities. An experiment is carried out to verify the acoustic performance of the proposed model. The experimental results, which agree well with those obtained numerically, show that the proposed structure yields high sound absorption peaks in a broadband frequency range. The proposed structure has potential significance for various underwater applications such as the acoustic coating and reducing vibration and noise.