Plate-type acoustic metamaterial with cavities coupled via an orifice for enhanced sound transmission loss

2018 ◽  
Vol 112 (5) ◽  
pp. 051903 ◽  
Author(s):  
Linus Yinn Leng Ang ◽  
Yong Khiang Koh ◽  
Heow Pueh Lee
Keyword(s):  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Transmission Loss ◽  
Acoustic Metamaterial ◽  
Plate Type

Excellent low-frequency sound absorption of radial membrane acoustic metamaterial

2017 ◽  
Vol 31 (03) ◽  
pp. 1750011 ◽  
Author(s):  
Nansha Gao ◽  
Jiu Hui Wu ◽  
Hong Hou ◽  
Lie Yu
Keyword(s):  
Transmission Loss ◽  
Low Frequency ◽  
Sound Transmission ◽  
Ring Structure ◽  
Circular Ring ◽  
Effective Density ◽  
Geometrical Parameters ◽  
Membrane Thickness ◽  
Sound Transmission Loss ◽  
Acoustic Metamaterial

This paper proposes a new radial membrane acoustic metamaterial (RMAM) structure, wherein a layer membrane substrate is covered with a rigid ring (polymethyl methacrylate frame and aluminum lump). The dispersion relationships, transmission spectra and displacement fields of the eigenmodes of this radial membrane acoustic metamaterial are studied with FEM. In contrast to the traditional radial phononic crystals (RPCs), the proposed structures can open bandgaps (BGs) in lower frequency range (0–300 Hz). Simulation results show that the physical mechanism behind the bandgaps is the coupling effects between the rotational vibration of aluminum lump and the transverse vibration of membrane. Geometrical parameters which can adjust the bandgaps’ widths or positions are analyzed. Finally, we investigate the axial sound transmission loss of this acoustic metamaterial structure, and discuss the effects of factor loss, membrane thickness and the number of layers of unit cell on the axial sound transmission loss. Dynamic effective density proves the accuracy of the FEM results. This kind of structure has potential application in pipe or circular ring structure for damping/noise reduction.

Experimental and numerical investigations of ventilated acoustic metamaterial based in-parallel arrangement of Helmholtz resonator for façade screen

2021 ◽  
Vol 263 (1) ◽  
pp. 5382-5390
Author(s):  
Denilson Ramos ◽  
Luís Godinho ◽  
Paulo Amado-Mendes ◽  
Paulo Mareze
Keyword(s):  
Potential Application ◽  
Noise Control ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Recent Effort ◽  
Sound Transmission Loss ◽  
Noise Mitigation ◽  
Acoustic Metamaterial ◽  
Numerical Investigations ◽  
Parallel Arrangement

Understanding urban noise as a serious environmental problem in urban centers, the development and application of noise control strategies have demanded a recent effort by several researches. In this case, the development of acoustic metamaterial artificially designed to manipulate the wave phenomena has become a recent topic, aiming at optimized responses, and enables the development of subwavelength devices with potential application in passive ventilation and noise mitigation, providing better environmental conditions in buildings. The present paper intends to contribute to the knowledge in this field by investigating the concept of an acoustic metamaterial with negative bulk modulus based in a parallel arrangement of Helmholtz Resonators. Experimental and numerical investigations are carried out to determine the acoustic potential of the proposed meta structure in terms of sound absorption and sound transmission loss. The developed concept exhibits significant benefits in the properties of sound transmission loss, and seems a potential application for noise control at specific frequency bands (mainly at low to middle frequency) in building façades.

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