Design and Sound Absorption Performance of a Laminated Structure Using Natural Materials

The broadband sound-absorption technology exploration is of great significance in acoustics, with wide applications in noise control and sound mitigation. In this work, natural materials were used for sound absorption. The straw and rice husk are abundant and easily accessible biological resources, considered excellent candidates as sound absorption materials for their natural porous structure. The sound absorption characteristics were evaluated by classifying the rice straw into thick, thin, and mixed groups, and the optimum thickness was clarified. The typical sound absorption materials were prepared from different kinds of rice straws (thickness) and rice husks. A systematic exploration was devoted to studying the rice straw type and cavity volume effects on the sound-absorbing performance. The results showed that rice straws with a diameter of ≥3 mm exhibited an optimized sound absorption capacity, and the performance continued to be enhanced after mixing with rice husks. In addition, the sound absorption performance on the low-frequency side of the multi-layer sound-absorbing structure, composed of porous medium density fiberboard, thick straw, and rice husk, was better than that of the multi-layer sound-absorbing structure using non-woven fabrics.