Compact broadband acoustic meta-silencer based on synergy between reactive and resistive units

Abstract

Acoustic silencers are the most effective solution to control noise in ducts. In this paper, we propose a compact acoustic meta-silencer (AMS) based on the synergy between reactive and resistive units that enables the reduction of low-frequency and broadband noise. We first propose a conceptual AMS comprising simple reactive and resistive units to verify its unique sound attenuation performance. To explore its potential for application, we then propose an advanced AMS unit consisting of two independent annular chambers that represent reactive and resistive units, respectively. The synergistic mechanism between reactive and resistive units to achieve superior sound attenuation is revealed. Next, the band structures of the infinite periodic advanced AMS are discussed, and three different types of advanced AMS containing six units are examined. It is demonstrated numerically and experimentally that the optimized AMS with a compact size can achieve a transmission loss higher than 15 dB over a super-wide low-frequency range (290–1344 Hz). The work here provides a new avenue for the design of low-frequency and broadband meta-silencers to control the noise in ducts.