Ultrathin and durable open metamaterials for simultaneous ventilation and sound reduction

Abstract

We report an ultrathin and durable open metamaterial capable of both fluid passage and noise insulation at low frequencies. The proposed open metamaterial, denoted as the perforated and constrained acoustic metamaterial (PCAM), contains a large orifice in each unit cell. An impedance-based model was established to investigate the working mechanism and acoustic performances of the PCAM and was then verified by measurements in a sound impedance tube. With only a thickness of 1.5 mm (0.19% of wavelength), a PCAM sample exhibits a sound transmission loss of 20 dB at 430 Hz. This high-efficiency soundproof feature under the ventilation condition is attributed to the interferences of the two wave fields between the orifice area and the plate area in the near-field. The PCAM may have potential applications in limited spaces requiring high-efficiency ventilation and long-time service.

Recent Advances in Acoustic Metamaterials for Simultaneous Sound Attenuation and Air Ventilation Performances

“…A simple jigsaw puzzle-like assembly technique was demonstrated to interconnect the multiple unit cells, which led to the production of an integrated acoustic architecture without further adhesives. Wang et al [95] experimentally investigated the acoustic performances of a perforated and constrained acoustic metamaterial (PCAM). The presented structure, eventually a part of the plate-type acoustic metamaterial category, was composed of the perforated plate and a rigid supporting frame.…”

Recent Advances in Acoustic Metamaterials for Simultaneous Sound Attenuation and Air Ventilation Performances

“…A simple jigsaw puzzlelike assembly technique was demonstrated to interconnect the multiple unit cells, which led to the production of an integrated acoustic architecture without further adhesives. Wang et al [94] experimentally investigated the acoustic performances of a perforated and constrained acoustic metamaterial (PCAM). The presented structure, eventually a part of the plate-type acoustic metamaterial category, composed of the perforated plate and a rigid supporting frame.…”

“…and constrained acoustic metamaterial and the measured transmission loss spectra. Reprinted with permission from Wang et al [94], ©2019 AIP Publishing LLC.…”

Broadband noise insulation of windows using coiled-up silencers consisting of coupled tubes

“…A total insertion loss of 8.8 dB can be achieved between 100 and 500 Hz with the hybrid silencer, and the insertion loss of the staggered window with the proposed silencers installed is shown to increase from 6.7 to 15.6 dBA between 100 and 2000 Hz for normal incident traffic noise. Compared with the recent work in noise insulation ventilation windows, which either work in a limited frequency band 28 , 29 , or in a broad band but at higher frequencies 26 , 30 , 31 , this work extends the working frequencies of the silencer to as low as 100 Hz, and increases the effective band width to 1900 Hz. Another improvement is that we carried out experiments with a real scale down model of a staggered window, instead of in an impedance tube with normal incident sound, thus demonstrated the feasibility of the silencer to be used in practical applications.…”