Broadband and low-frequency sound absorption of modified Helmholtz resonator combined with porous layer addition

Vergara, Erasmo F.; Almeida, Gildean do N.; Barbosa, Leandro Rodrigues; Lenzi, Arcanjo; Sousa, Augusto Carvalho de

doi:10.1063/5.0108807

Cited by 12 publications

(3 citation statements)

References 40 publications

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“…With typical strongly enhanced acoustic fields and subwavelength structural scale, the initial designs of sound-absorbing metamaterials are remarkably efficient for narrow-band performances [17][18][19][20][35][36][37][38][39]. In pursuit of broadband sound absorption/attenuation, an efficient approach is to combine a series of component acoustic absorbers operating at different frequencies [31,34,[40][41][42][43][44][45][46][47][48][49][50][51][52]. Despite the fascinating achievements of high-efficiency broadband sound absorption/attenuation, it still remains a significant gap in the realization of timbre manipulation since timbre manipulation puts higher demands on the frequency-selective and delicate modulation of resonances in broadband.…”

Section: Introductionmentioning

confidence: 99%

Meta-silencer with designable timbre

Wang

Zhou

Qiu

et al. 2023

Int. J. Extrem. Manuf.

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Timbre, as one of the essential elements of sound, plays an important role in determining sound properties, whereas its manipulation has been remaining challenging for passive mechanical systems due to the intrinsic dispersion nature of resonances. Here, we present a meta-silencer supporting intensive mode density as well as highly tunable intrinsic loss and offering a fresh pathway for designable timbre in broadband. Strong global coupling is induced by intensive mode density and delicately modulated with the guidance of the theoretical model, which efficiently suppresses the resonance dispersion and provides desirable frequency-selective wave-manipulation capacity for timbre tuning. As proof-of-concept demonstrations for our design concepts, we propose three meta-silencers with the designing targets of high-efficiency broadband sound attenuation, efficiency-controlled sound attenuation and designable timbre, respectively. The proposed meta-silencers all operate in a broadband frequency range from 500 to 3200 Hz and feature deep-subwavelength sizes around 50 mm. Our work opens up a fundamental avenue to manipulate the timbre with passive resonances-controlled acoustic metamaterials and may inspire the development of novel multifunctional devices in noise-control engineering, impedance engineering, and architectural acoustics.

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Section: Introductionmentioning

confidence: 99%

Meta-silencer with designable timbre

Wang

Zhou

Qiu

et al. 2023

Int. J. Extrem. Manuf.

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show abstract

“…11 In 2022, Vergara et al designed a hybrid acoustic metamaterial consisting of a porous layer with a modified Helmholtz cavity for broadband sound absorption. 12 Therefore, the Helmholtz cavity structure with an optimized design can achieve effective control of low-frequency noise.…”

Section: Introductionmentioning

confidence: 99%

Low-frequency sound-absorbing metamaterial based on a series-parallel arrangement structure

Zhuang,

Cui,

2023

Journal of Low Frequency Noise, Vibration and Active Control

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Low-frequency noise has a long wavelength, decays very slowly, and is extremely penetrating. Traditional marine acoustic insulation materials have difficulty achieving effective control of this low-frequency noise. In this paper, a series-parallel arrangement structure of a low-frequency metamaterial is designed, which mainly comprises convoluted channels and Helmholtz cavities in series and a sandwich arrangement of multiple cells (as opposed to the traditional parallel arrangement). We use a numerical method to establish an acoustic-solid coupling model for the metamaterial, consider the influence of thermal and viscous losses on its sound absorption performance, and investigate the sound absorption characteristics and mechanisms of the single-cell and multicell structures. The metamaterial designed in this paper shows an average absorption coefficient of 0.97 in the range of 130–145 Hz. An experimental model was prepared by 3D printing, and the intended sound absorption effect was experimentally verified.

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“…Their sound absorption has been extensively studied [17,18] and various improvements have been proposed [19,20]. Also, various combinations with porous absorbers have been found to improve their acoustic performance [21]. Their sound absorption can be evaluated with appropriate sources [22,23] and excitation signals [24].…”

Section: Introductionmentioning

confidence: 99%

Tunable Helmholtz Resonators Using Multiple Necks

Papadakis,

Stavroulakis

2023

Micromachines

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One of the uses of Helmholtz resonators is as sound absorbers for room acoustic applications, especially for the low frequency range. Their efficiency is centered around their resonance frequency which mainly depends on elements of their geometry such as the resonator volume and neck dimensions. Incorporating additional necks on the body of a Helmholtz resonator (depending on whether they are open or closed) has been found to alter the resulting resonance frequency. For this study, tunable Helmholtz resonators to multiple resonance frequencies, are proposed and investigated utilizing additional necks. The resonance frequencies of various multi-neck Helmholtz resonators are first modeled with the use of the finite element method (FEM), then calculated with the use of an analytical approach and the results of the two approaches are finally compared. The results of this study show that Helmholtz resonators with multiple resonances at desired frequencies are achievable with the use of additional necks, while FEM and analytical methods can be used for the estimation of the resonance frequencies. Analytical and FEM approach results show a good agreement in cases of small number of additional necks, while the increasing differences in cases of higher neck additions, were attributed to the change in effective length of the necks as demonstrated by FEM. The proposed approach can be useful for tunable sound absorbers for room acoustics applications according to the needs of a space. Also, this approach can be applied in cases of additional tunable air resonances of acoustic instruments (e.g., string instruments).

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Broadband and low-frequency sound absorption of modified Helmholtz resonator combined with porous layer addition

Cited by 12 publications

References 40 publications

Meta-silencer with designable timbre

Meta-silencer with designable timbre

Low-frequency sound-absorbing metamaterial based on a series-parallel arrangement structure

Tunable Helmholtz Resonators Using Multiple Necks

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