Ultra-broadband sound absorption via a parallel composite structure consisting of perforated panel resonators with tube bundles and porous material

An ultra-broadband composite sound absorber composed of perforated panel resonators with tube bundles (PPTB) and porous sound absorbing materials (PSAM) is designed. The PPTB is established by utilizing multiple resonators with different resonance frequencies to obtain continuous low-frequency broadband absorption. By introducing PSAM in a proper manner around PPTB, the surface impedance of the structure is matched with air over a broader frequency range. As a result, the composite absorber designed with PPTB and PSAM achieves ultra-broadband sound absorption performance through the coupling effects of low-frequency resonance absorption by PPTB and high-frequency energy dissipation by PSAM. The acoustic-electrical analogy model and the finite-element method are applied to analyze the sound absorption performance. The results show that the composite structure has an average absorption coefficient of 0.93 in the ultra-broadband frequency range of 400 Hz–10 kHz. Moreover, the influence of structural parameters on the sound absorption performance is discussed, and the coupling sound absorption efficiency of PPTB unit under different damping states is compared. The impedance tube measurements validate that the ultra-broadband composite structure exhibits remarkable sound absorption properties within the frequency range of 400 Hz–1600 Hz. In comparison with porous materials of the same thickness, this composite sound absorber significantly enhances its low-frequency absorption performance.