Acoustic metamaterial panel for both fluid passage and broadband soundproofing in the audible frequency range

Abstract

We present the design, including an experimental demonstration, of an acoustic metamaterial panel aimed at reducing incoming broadband noise in the audible frequency range while allowing an incoming fluid to pass through the holes formed in the panel. The noise reduction performance of the proposed acoustic metamaterial panel is attributed to an array of annular cavities enclosing the fluid passage holes. The acoustic behavior of the acoustic metamaterial panel is theoretically analyzed by the transfer matrix method, and an equivalent acoustic impedance of each annular cavity is included with its effective length in the derived transfer matrix. The effective bulk modulus for the acoustic metamaterial panel is then extracted from the transmission and reflection coefficients by using the retrieval method. It is shown that the frequency range of the negative effective bulk modulus coincides with the stop band of the acoustic metamaterial panel. The underlying physical mechanism for the negative effective bulk modulus is attributed to the out-of-phase motion of vibrating particles in adjacent annular cavities. A calculated transmission coefficient curve of the acoustic metamaterial panel is shown to be in good agreement with the measured one. The findings presented in this work should be useful in the design of a holey soundproof panel.

The Present and Future Role of Acoustic Metamaterials for Architectural and Urban Noise Mitigations

“…A maximum transmission loss of 40 dB is achieved through the structure signifying its potential for future applications. Jung et al [82] presented a muffler type acoustic metamaterial panel for ventilated sound attenuation. As shown in Figure 6c, each unit cell of the metapanel consisted of one circular duct enclosed by an array of annular cavities.…”

Influence of geometric structure, convection, and eddy on sound propagation in acoustic metamaterial with turbulent flow

“…2(a), as the frequency increases initially, the sound pressure level values decrease rapidly, have a minimum value at a specific frequency (4529.1 Hz in the case of N=5), and then rise again. In other words, it has a resonant property, which can be treated as the result of the interaction between the particle vibration in the direction of sound propagation in the circular duct and the particle vibration perpendicular to the direction of sound propagation in the annular cavity [14]. This property appears regardless of the number of annular cavities.…”

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

“…A finite element based theoretical and numerical approach was used to evaluate the sound characteristics in the frequency range of 125 Hz to 2000 Hz. Jung et al [93] demonstrated an acoustic metamaterial panel for both fluid passage and broadband soundproofing in the audible frequency range of 2000 Hz to 4000 Hz. The unit cell of the panel consisted of a circular through duct enclosed with multiple annular circumferential cavities.…”