Development of composite sound absorbing material combining porous material and a resonator by additive manufacturing

In recent years, the development of sound-absorbing materials has focused on integrating different sound absorption mechanisms into composite structures to achieve a broadband sound absorption effect. Ensuring the performance of such composite structures requires high-precision fabrication. This study aims to fabricate porous sound absorbers and Helmholtz resonators by additive manufacturing and to develop composite structural sound absorbers by integrating these components. First, a three-dimensional periodic structure was fabricated using a specially designed porous resin, and its sound absorption coefficients were measured to confirm its effectiveness as a porous sound-absorbing material. Then, this structure was combined with a slit-type Helmholtz resonator in various configurations to form a composite absorber. The results suggested that porous materials designed with the porous resin and three-dimensional periodic structures exhibited good sound absorption performance. This porous material can be formed into a variety of shapes as needed and easily integrated into a resonator in various ways. Additionally, integrating the periodic structure made of porous resin with the Helmholtz resonator significantly improved the sound absorption performance and broadened its frequency range, demonstrating the effectiveness of the proposed structure.