A design method for accurate acoustic impedance matching under coherent coupling of sound-absorbing subunits

Abstract

Acoustic metamaterials have garnered significant attention as an effective means to control low-frequency noise. However, the accurate design of complex structures composed of multiple subunits is still a challenge due to local coupling effects. To address this issue, in this work, a new design method is proposed that accurately achieves impedance matching at the target frequency when subunits are coupled in parallel. The method is demonstrated using six Fabry–Pérot (F–P) tubes to achieve perfect sound absorption in the continuous band of 405–445 Hz and the discontinuous bands of 400–410 and 430–440 Hz. Theoretical results show an average absorption coefficient of 99.3% in the target frequency band, which is verified through an impedance tube experiment. In addition, this paper explores the stability of this method under complex design conditions and discusses the mechanism of the influence of subunit parameters on sound-absorption performance from the perspective of impedance matching. Overall, the proposed design method offers a promising approach to achieving broadband sound absorption using multiple coupled subunits. The results of this study provide valuable insights for future research and the design of acoustic metamaterials.