Design and Fabrication of Double-Cavity Resonant Structure toward Low-Frequency Sound Absorption Improvement

Exploring broadband sound-absorption technology is of great significance in acoustics, with wide applications in noise control and sound mitigation. In this work, a multiband sound-absorbing device was proposed with two air cavities. A double resonant structure was constructed by embedding a sound-absorbing material in the Helmholtz resonator’s neck and a microperforated board inside the Helmholtz resonator, respectively. In particular, we systematically discussed the sound absorption coefficient of each assembly unit and shed light on the mechanism and structure-activity relationship of the proposed double-cavity resonant device (DCRD). The results showed that the sound absorption performance of the prepared DCRD was about twice higher than that of the Helmholtz resonance structure under the same air cavity content. Thus, it could greatly improve the absorption ratio of low-frequency sound without sacrificing high-frequency performance with the microperforated plate assistance. Overall, we believe this work provides a new toolbox to enrich the family of resonant sound absorption materials, especially realizing noise reduction optimization of low-frequency sounds through a flexible design approach.