Broadband Low-Frequency Acoustic Metamuffler

In this research, we propose and design an acoustic metamuffler (AMM) by coupling a microperforated plate and a composite waveguide formed by a main waveguide and a Helmholtz resonator. The proposed mechanism and deliberately designed structure are conducive to generating multimode resonances that help to improve the coupling absorption effect and lead to broadband (4 octaves) sound insulation. We develop an effective circuit model to analytically predict the insulation bandwidth and put forward numerical and experimental measurements that demonstrate the effectiveness of the proposed concept. The designed AMM produces sound insulation with an average of 20 dB of sound-transmission loss at a low-frequency range, extending from 100 to 1600 Hz, while having an ultrathin thickness of 6.2 cm (1/55 lambda for the lowest working frequency). Our findings could have pragmatic applications for acoustic insulators or absorbers.

Automated summary

The research introduces an acoustic metamuffler (AMM) which effectively achieves broadband sound insulation with high sound transmission loss at low frequencies. The proposed concept is supported by analytical predictions using a circuit model and confirmed through numerical and experimental measurements.