To enhance the stealth of underwater structures and improve the low-frequency (500 ~ 1 000 Hz) sound absorption performance of traditional locally resonant acoustic metamaterials (LRAMs), a novel type of LRAMs incorporating multiple embedded scatterers with a radius gradient was proposed based on local resonance coupling. The band gap characteristics were investigated using the finite element method (FEM), and the influence of coupling resonance on band gap behavior was analyzed. The sound absorption coefficient within 5 000 Hz was calculated, and the effects of scatterer number, shape, radius gradient, and backing thickness on absorption performance were examined. Additionally, the modulation mechanism of structural modifications on low-frequency absorption below 1 000 Hz was explored. The results indicate that the novel LRAMs improve low-frequency sound absorption performance through the coupling resonance effect between scatterers, and further optimization of the material's structural parameters can enhance the absorption performance of the LRAMs.