Laboratory measurement of the acoustic absorption coefficient based on the modal dispersion

2013 ◽  
Vol 134 (5) ◽  
pp. 4004-4004
Author(s):  
Jevgenija Prisutova ◽  
Kirill Horoshenkov ◽  
Jean-Philippe Groby ◽  
Bruno Brouard
Keyword(s):  
Absorption Coefficient ◽  
Laboratory Measurement ◽  
Acoustic Absorption ◽  
Modal Dispersion ◽  
Acoustic Absorption Coefficient

Low-frequency sound absorption of a tunable multilayer composite structure

2021 ◽  
pp. 107754632110082
Author(s):  
Hanbo Shao ◽  
Jincheng He ◽  
Jiang Zhu ◽  
Guoping Chen ◽  
Huan He
Keyword(s):  
Porous Material ◽  
Absorption Coefficient ◽  
Composite Structure ◽  
Low Frequency ◽  
Acoustic Absorption ◽  
Multilayer Composite ◽  
Absorption Frequency ◽  
Acoustic Absorption Coefficient ◽  
Simulation And Experiment ◽  
Single Material

Our work investigates a tunable multilayer composite structure for applications in the area of low-frequency absorption. This acoustic device is comprised of three layers, Helmholtz cavity layer, microperforated panel layer, and the porous material layer. For the simulation and experiment in our research, the absorber can fulfill a twofold requirement: the acoustic absorption coefficient can reach near 0.8 in very low frequency (400 Hz) and the range of frequency is very wide (400–3000 Hz). In all its absorption frequency, the average of the acoustic absorption coefficient is over 0.9. Besides, the absorption coefficient can be tunable by the scalable cavity. The multilayer composite structure in our article solved the disadvantages in single material. For example, small absorption coefficient in low frequency in traditional material such as microperforated panel and porous material and narrow reduction frequency range in acoustic metamaterial such as Helmholtz cavity. The design of the composite structure in our article can have more wide application than single material. It can also give us a novel idea to produce new acoustic devices.

The effect of the combination of multiple woven fabric and nonwoven on acoustic absorption

2019 ◽  
pp. 152808371985877 ◽  
Author(s):  
Pilar Segura-Alcaraz ◽  
Jorge Segura-Alcaraz ◽  
Ignacio Montava ◽  
Marilés Bonet-Aracil
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Woven Fabric ◽  
Sound Absorption Coefficient ◽  
Acoustic Absorption ◽  
Experimental Conditions ◽  
Resistive Layer ◽  
Textile Materials ◽  
Acoustic Absorption Coefficient ◽  
Fabric Structures

Textile materials can be used as acoustic materials. In this study, the acoustic absorption coefficient of multilayer fabrics with 60 ends/cm and 15, 30, 45, and 60 picks/cm is measured when the fabric is added as a resistive layer on top of a polyester nonwoven, in order to study the influence of the fabric spatial structure in the acoustic absorption of the assembly. Five different fabric structures are used. Design of experiments and data analysis tools are used to describe the influence of two manufacturing factors on the sound absorption coefficient of the ensemble. These factors are the fabric weft count (picks/cm) and the thickness of the nonwoven (mm). The experimental conditions under which the maximum sound absorption coefficient is achieved are found. The influence of each factor and a mathematical model are obtained. Results of statistical and optimization analysis show that for the same fabric density, sound absorption coefficient increases as the number of layers decreases.

Acoustic Properties of Materials for Vibration Reduction and Resistance on Ultra-Precision Machine

2014 ◽  
Vol 620 ◽  
pp. 140-145
Author(s):  
Dan Huang ◽  
Ying Wang
Keyword(s):  
Absorption Coefficient ◽  
Porous Ceramic ◽  
Vibration Reduction ◽  
Calculation Model ◽  
Acoustic Energy ◽  
Acoustic Properties ◽  
Acoustic Absorption ◽  
Cylindrical Pore ◽  
Acoustic Absorption Coefficient ◽  
Ultra Precision

The porous ceramic holds good potential as acoustic resistance and vibration reduction material during ultra-precision machining. Porous materials absorb acoustic energy by friction with the air that moves inside the pores, and in this paper, the motion is simplified as the incompressible fluid in a single cylindrical pore. The analysis and calculation results show that the acoustic coefficient of porous ceramic is a complicated wave function and the acoustic absorption coefficient calculation model is feasible based on fluid thermal viscous theory. The acoustic absorption coefficient of porous ceramic increases with the increase of thickness, and its period and amplitude decreases with the increase of porosity of ceramic.

scholarly journals Experimental Sound Absorption of Several Loose Uncooked Granular Materials

2019 ◽  
Vol 9 (1) ◽  
pp. 4578-4583
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Grain Shape ◽  
Experimental Tests ◽  
Sound Absorption Coefficient ◽  
Acoustic Absorption ◽  
Low Frequencies ◽  
Acoustic Insulation ◽  
Acoustic Absorption Coefficient ◽  
First Time

Absorbent materials it's an acoustic solution that can be used to control the reverberation time (RT) in deferent spaces as: conference rooms, in halls, theaters, cinema.... and also, it can be used in walls or ceilings of buildings to improve the acoustic insulation Which can be used for internal separations between spaces. This study focuses on the experimental study of the acoustic absorption coefficient of several granular food materials as a function of frequency 50 to 1600 Hz. All acoustic absorption tests performed in this study are performed by an acoustic impedance tube or Kundt tube. And to the knowledge of the author it is the first time in the literature that someone studies the acoustic behavior of this kind of materials. Several parameters were studied such as the effect of thickness on the sound absorption coefficient of the materials tested, like the influence of the grain form on the acoustic absorption by the introduction of a new parameter L / D, and finally the influence of density and type of material on the sound absorption coefficient. The objective of this work is to study the influence of the grain shape on the sound absorption coefficient, and that's why we have chosen these fifteen materials each one with its own shape. The results of these experimental tests show that when the sample thickness rises, the acoustic absorption coefficient rises too with a shift from resonance frequency to low frequencies. When the L/D parameter rises, the absorption behavior increases too in all frequencies mentioned. Finally, as the density of the tested material rises, the percentage of sound absorption of the materials also rises

Acoustic absorption coefficient of open-cell polyolefin-based foams

2014 ◽  
Vol 121 ◽  
pp. 26-30 ◽  
Author(s):  
Mónica Álvarez-Láinez ◽  
Miguel Angel Rodríguez-Pérez ◽  
Jose Antonio de Saja
Keyword(s):  
Absorption Coefficient ◽  
Acoustic Absorption ◽  
Open Cell ◽  
Acoustic Absorption Coefficient
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