scholarly journals Sound Absorption Properties of Aluminum Sponges Manufactured by Infiltration Process

2010 ◽  
Vol 146-147 ◽  
pp. 1651-1654 ◽  
Author(s):  
Patricia M. Fernández ◽  
Luis J.R. Cruz ◽  
Luis E. García Cambronero ◽  
Cesar Díaz ◽  
María Ángeles Navacerrada
Keyword(s):  
Pore Size ◽  
Sound Absorption ◽  
Frequency Range ◽  
Absorption Factor ◽  
Absorption Properties ◽  
Infiltration Process ◽  
Interconnected Porosity ◽  
Factor Α

In this paper, the sound absorption properties of aluminum sponges manufactured by infiltration process have been studied. The results show that the sound absorption factor α changes in function of pore size. Additionally, the sound absorption factor α was sensitive to the frequency range measured and it was depending of the thickness sample. It was found that the interconnected porosity plays an important role increasing the sound absorption properties of the aluminum sponges studied.

scholarly journals Acoustic Panels Made of Paper Sludge and Clay Composites

2021 ◽  
Vol 13 (2) ◽  
pp. 637
Author(s):  
Tomas Astrauskas ◽  
Tomas Januševičius ◽  
Raimondas Grubliauskas
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Composite Panel ◽  
Sound Absorption Coefficient ◽  
Core Material ◽  
Paper Sludge ◽  
Frequency Range ◽  
Absorption Properties ◽  
Air Gaps ◽  
The Core

Studies on recycled materials emerged during recent years. This paper investigates samples’ sound absorption properties for panels fabricated of a mixture of paper sludge (PS) and clay mixture. PS was the core material. The sound absorption was measured. We also consider the influence of an air gap between panels and rigid backing. Different air gaps (50, 100, 150, 200 mm) simulate existing acoustic panel systems. Finally, the PS and clay composite panel sound absorption coefficients are compared to those for a typical commercial absorptive ceiling panel. The average sound absorption coefficient of PS-clay composite panels (αavg. in the frequency range from 250 to 1600 Hz) was up to 0.55. The resulting average sound absorption coefficient of panels made of recycled (but unfinished) materials is even somewhat higher than for the finished commercial (finished) acoustic panel (αavg. = 0.51).

Method of Testing of Sound Absorption Properties of Materials Intended for Ultrasonic Noise Protection

2013 ◽  
Vol 38 (2) ◽  
pp. 191-195 ◽  
Author(s):  
Dariusz Pleban
Keyword(s):  
Sound Absorption ◽  
Free Field ◽  
Tone Burst ◽  
Mineral Wool ◽  
Frequency Range ◽  
Absorption Properties ◽  
Open Cell Foam ◽  
Properties Of Materials ◽  
Cell Foam

Abstract Efficient ultrasonic noise reduction by using enclosures requires the knowledge of absorbing properties of materials in the frequency range above 4 kHz. However, standardized methods enable determination of absorption coefficients of materials in the frequency range up to 4 kHz. For this reason, it is proposed to carry out measurements of the sound absorption properties of materials in the free field by means of a tone-burst technique in the frequency range from 4 kHz to 40 kHz at angles of incidence varying from 0° to 60°. The absorption coefficient of a material is calculated from the reflection coefficient obtained by reflecting a tone-burst from both a perfectly reflecting panel and a combination of this panel and the sample of the tested material. The tests results show that mineral wool and polyurethane open-cell foam possess very good absorbing properties in this frequency range.

Analysis of Sound Absorption Properties of Three-Leaf Microperforated Panel Absorbers without a Rigid Backing

2014 ◽  
Vol 937 ◽  
pp. 465-471
Author(s):  
Xiao Ling Gai ◽  
Xian Hui Li ◽  
Rui Wu ◽  
Bin Zhang ◽  
Jun Juan Zhao
Keyword(s):  
Sound Absorption ◽  
Low Frequency ◽  
Wide Frequency Range ◽  
Structure Design ◽  
Frequency Region ◽  
Theoretical Development ◽  
Frequency Range ◽  
Absorption Properties ◽  
High Frequency Region ◽  
Energy Dissipated

Microperforated panel (MPP) absorbers have been developed rapidly and used in many fields in recent years. First, based on the Maa’s theory, the theoretical development of MPP is reviewed in this paper. Furthermore, structure design and processing technology of MPP are introduced. Finally, the further development of MPP is discussed. Based on the MPP theory and electro-acoustical equivalent circuit principle, sound absorption properties of three-leaf microperforated panel (TMPP) absorbers without a rigid backing are studied to broaden the sound absorption bandwidth of MPP structure. Simulation results show that TMPP absorbers without a rigid backing have two resonance peaks and the energy dissipated coefficient remains constant in the low frequency range. The resonance frequency moves toward low frequency region with the increasing of the distance, thickness and pore diameter of MPP and moves toward high frequency region with the increasing of the perforation when other parameters keep invariant. The energy dissipated coefficient more than 0.5 over 8 octaves by choosing proper parameters. In conclusion, TMPP absorbers without a rigid backing have good sound absorption properties in a wide frequency range.

scholarly journals Sound Absorption Properties of Materials Based on Recycled Plastic Granule Mixtures

2021 ◽  
Vol 29 (1) ◽  
pp. 15-19
Author(s):  
Andrea Biskupičová ◽  
Miriam Ledererová ◽  
Stanislav Unčík ◽  
Christ Glorieux ◽  
Monika Rychtáriková
Keyword(s):  
Absorption Spectrum ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Ethylene Vinyl Acetate ◽  
Frequency Range ◽  
Absorption Properties ◽  
Audible Frequency ◽  
Properties Of Materials ◽  
Two Peaks ◽  
Foam Plastics

Abstract This article reports on impedance tube measurements of the sound absorption coefficient α (-) of selected recycled foam plastics, i.e., ethylene-vinyl acetate (EVA), polyvinyl chloride (PVC), polystyrene (PS), and polypropylene (PP), in different mixtures with a binding adhesive. The effect of the thickness of the sample on the sound absorption spectrum as well as the variability in absorption across the different samples of the same composition and thickness are discussed. For the EVA/ PP and PS/PP mixtures, the spectrum is characterized by two peaks that shift as the thickness is changing. These mixtures were also found to be the most absorbent across the whole audible frequency range.

scholarly journals An innovative composite plywood for the acoustic improvement of small closed spaces

Holzforschung ◽  
2017 ◽  
Vol 71 (6) ◽  
pp. 521-526
Author(s):  
Francesco Negro ◽  
Corrado Cremonini ◽  
Marco Fringuellino ◽  
Roberto Zanuttini
Keyword(s):  
Sound Absorption ◽  
Resonance Effect ◽  
Low Frequency ◽  
Frequency Range ◽  
Honeycomb Core ◽  
Final Size ◽  
Absorption Properties ◽  
Reverberation Chamber ◽  
The Core ◽  
Dining Room

Abstract Poor acoustics is a common problem in many small closed rooms such as offices or dining rooms. Sound absorbing panels used as wall or ceiling coverings can be a remedy. In the present paper, the sound absorption properties of a composite made of two plywood skins bonded to an inner honeycomb core of plywood cells, designed by the authors in a previous study, were improved by drilling the surfaces. The holes communicate with the void cells of the core, activating the Helmholtz resonance effect. The acoustic behavior of small specimens and final-size samples are described, which were also tested in a reverberation chamber and in a real dining room. The developed lightweight composite plywood achieved αmax 0.90 values (maximal sound absorption coefficients) around 400 Hz, i.e. in the low frequency range, resulting in being well suited for various acoustic improvements.

scholarly journals Fabrication of Millable Polyurethane Elastomer/Eucommia Ulmoides Rubber Composites with Superior Sound Absorption Performance

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7487
Author(s):  
Yuhang Dong ◽  
Dexian Yin ◽  
Linhui Deng ◽  
Renwei Cao ◽  
Shikai Hu ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Polyurethane Elastomer ◽  
Eucommia Ulmoides ◽  
Frequency Range ◽  
Rubber Composites ◽  
Absorption Properties ◽  
Absorbing Materials ◽  
Absorption Performance ◽  
Blending Process ◽  
Physical Blending

Sound absorbing materials combining millable polyurethane elastomer (MPU) and eucommia ulmoides rubber (EUG) were successfully fabricated via a physical blending process of EUG and MPU. The microstructure, crystallization performances, damping, mechanical and sound absorption properties of the prepared MPU/EUG composites were investigated systematically. The microstructure surface of various MPU/EUG composites became rough and cracked by the gradual incorporation of EUG, resulting in a deteriorated compatibility between EUG and MPU. With the increase of EUG content, the storage modulus (E’) of various MPU/EUG composites increased in a temperature range of −50 °C to 40 °C and their loss factor (tanδ) decreased significantly, including a reduction of the tanδ of MPU/EUG (70/30) composites from 0.79 to 0.64. Specifically, the addition of EUG sharply improved the sound absorption performances of various MPU/EUG composites in a frequency range of 4.5 kHz–8 kHz. Compared with that of pure MPU, the sound absorption coefficient of the MPU/EUG (70/30) composite increased 52.2% at a pressure of 0.1 MPa and 16.8% at a pressure of 4 MPa, indicating its outstanding sound absorption properties.

Characterisation of microstructural and sound absorption properties of porous asphalt subjected to progressive clogging

2021 ◽  
Vol 283 ◽  
pp. 122654
Author(s):  
Mohd Zul Hanif Mahmud ◽  
Norhidayah Abdul Hassan ◽  
Mohd Rosli Hainin ◽  
Che Ros Ismail ◽  
Ramadhansyah Putra Jaya ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Absorption Properties ◽  
Porous Asphalt

Optimization and Modeling of Sound-Absorption Properties of Natural Fibers for Acoustical Application

2021 ◽  
pp. 1-17
Author(s):  
Seyed Ehsan Samaei ◽  
Ebrahim Taban ◽  
Umberto Berardi ◽  
Seyyed Mohammad Mousavi ◽  
Mohammad Faridan ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Natural Fibers ◽  
Absorption Properties

scholarly journals Diffuse Sound Absorptive Properties of Parallel-Arranged Perforated Plates with Extended Tubes and Porous Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1091 ◽  
Author(s):  
Dengke Li ◽  
Daoqing Chang ◽  
Bilong Liu
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Porous Materials ◽  
Sound Absorption ◽  
Azimuthal Angle ◽  
Octave Band ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Perforated Plates ◽  
Absorption Performance

The diffuse sound absorption was investigated theoretically and experimentally for a periodically arranged sound absorber composed of perforated plates with extended tubes (PPETs) and porous materials. The calculation formulae related to the boundary condition are derived for the periodic absorbers, and then the equations are solved numerically. The influences of the incidence and azimuthal angle, and the period of absorber arrangement are investigated on the sound absorption. The sound-absorption coefficients are tested in a standard reverberation room for a periodic absorber composed of units of three parallel-arranged PPETs and porous material. The measured 1/3-octave band sound-absorption coefficients agree well with the theoretical prediction. Both theoretical and measured results suggest that the periodic PPET absorbers have good sound-absorption performance in the low- to mid-frequency range in diffuse field.

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