Acoustic multi-layer Helmholtz resonance metamaterials with multiple adjustable absorption peaks

Abstract

The single Helmholtz resonator obtains only one absorption peak in the broad frequency range, which limits its application in reducing the noise with multiple spectra. This paper reports an acoustic multi-layer Helmholtz resonance metamaterial, which can achieve multiple absorption peaks at given low-frequency targets. Meanwhile, through adjusting structural parameters of the multi-layer Helmholtz resonator, its impedance can be altered correspondingly to realize the absorption of noise with the multi groups of specific frequencies. In this paper, in order to achieve fine absorption performance with the specific frequencies of 100 and 400 Hz for a substation noise source, the sound absorption principle of a classical Helmholtz resonator with the embedded aperture is introduced theoretically, and then two series of multi-layer Helmholtz resonance structures with different parameters are designed. Thickness of the multi-layer structure is only 1/30th of the working wavelength, and two groups of resonance peaks are generated at 100 and 400 Hz, respectively. A finite element model of the multi-layer Helmholtz resonator is constructed to simulate its absorption performance. The samples are fabricated through the 3D light-curing printing, and their sound absorption performances are detected by the standing wave method. The simulation results are in good agreement with the experimental data, and two peaks with near-perfect absorptions are achieved at the target frequencies. The multi-layer Helmholtz resonator for achievement of three groups of absorption peaks is proposed later. This work provides an effective method to design a sound absorber with multiple absorption peaks, which can promote the application of acoustic metamaterials.

Development of Adjustable Parallel Helmholtz Acoustic Metamaterial for Broad Low-Frequency Sound Absorption Band

“…The sound absorption effect of APH-AM was realized by the resonance effect of the resonators with the same parameters and the coupling effect among the resonators with the different parameters [ 45 , 46 , 47 , 48 ], which could be judged from the distribution of acoustic pressure at the resonance frequencies obtained in acoustic finite element simulation models for the two APH-AM samples with normal incidence, as shown in the Figure 12 . The whole 3D structural model, the whole gridded model and the gridded model of APH-AM were shown in the Figure 12 a–c respectively, which were constructed similarly with the finite element simulation model for the double resonators in the Figure 2 .…”

Development and Optimization of Broadband Acoustic Metamaterial Absorber Based on Parallel–Connection Square Helmholtz Resonators

“…Owing to the inevitable noise resulted from the working equipment, an effective method to reduce the damage of noise is to place the sound absorbing materials around the noise source. Thus, many kinds of sound absorbing materials and structures have been developed, such as the porous materials [ 4 ], microperforated panel absorber [ 5 ], acoustic metamaterial [ 6 ], et al These developed sound absorbing materials and structures can be helpful for noise suppression.…”

Acoustic Metamaterials for Low-Frequency Noise Reduction Based on Parallel Connection of Multiple Spiral Chambers

“…The most effective strategy to broaden the sound absorption bandwidth is to combine the various resonant response units [ 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. It is difficult to accurately modulate the resonance frequencies of multiple units in the membrane AM due to the difficulty in controlling the membrane tension, so it is seldom used in low-frequency broadband noise control.…”

“…On the other hand, to achieve the perfect sound absorption, the acoustic impedance of the FP channel is matched to the acoustic impedance of the air, which means that the length of the channel should be close to the 1/4 wavelength [ 37 ]. In the low-frequency region, the thickness of a quarter wavelength represents a very large structure ( ).…”