A hybrid acoustic structure for low-frequency and broadband underwater sound absorption

The underwater anechoic coating with local resonant units is an effective method to achieve low-frequency sound absorption. However, the structure obtained in this way not satisfactory absorption effect of mid-high frequency bands. Capitalizing on impedance gradient characteristics functionally graded materials (FGMs) can improve matching between and medium, enhance dissipation waves inside structure. Based these, we propose acoustic structure, which obtain broadband performance by embedding resonators into FGMs. To reveal sound-absorbing mechanism further optimize conduct quantitative analyses parameters FGMs, forms resonators. results indicate that appropriately adjusting studied parameters, different peak be effects are also improved.