<p>Design of advanced sound absorption materials is crucial to the effective noise control in various environments, particularly in underwater acoustics. We propose a novel second-order Helmholtz resonator design featuring an extended neck and rubber coating, arranged in a vertical second-order configuration as an enhancement of the traditional Helmholtz resonator. A comprehensive numerical calculation and simulation model are developed to thoroughly investigate the absorption mechanism of the proposed structure and analyze the impact of the key parameters on its acoustic performance, such as resonator shape and material properties. To further enhance the sound absorption capabilities, the performance is optimized by utilizing a coupled configuration with two second-order quasi-Helmholtz resonators arranged in parallel. This design not only improves the overall absorption efficiency but also broadens the effective frequency range. The results demonstrate that the proposed acoustic metamaterial exhibits exceptional characteristics, including compact size, effective low-frequency wideband sound absorption, and potential applications in efficient underwater low-frequency sound absorption devices, offering promising solutions for noise control in marine environments.</p>