Analysis of Absorption Coefficient for Eco-Friendly Acoustical Absorbers

2013 ◽  
Vol 831 ◽  
pp. 58-61
Author(s):  
Jun Oh Yeon ◽  
Kyoung Woo Kim
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Glass Wool ◽  
Absorption Coefficients ◽  
Sound Absorber ◽  
Reduction Coefficient ◽  
Absorption Performance ◽  
Rock Wool

Primarily used for domestic buildings as a sound absorber are glass wool, rock wool, etc. These absorbers as well as waste absorber created by recycling wastes, PP+PET fiber absorber made from polypropylene and polyester, wood wool board bonded with finely sliced roots of trees and foamed aluminum absorber are recyclable eco-friendly absorbers that are constantly being developed. In this study, we compared the sound absorption performance of currently used absorbers and eco-friendly building absorbers. As a result, the NRC (Noise Reduction Coefficient) was found to be 0.85 for glass wool, 0.95 for rock wool, and 0.70 for polyester, 0.65 for waste absorber, 0.75 for PET+ PP fiber absorber, 0.40 for wood wool board, and 0.75 for foamed aluminum absorber. Based on the results of these absorption coefficients, we expect the usability of the absorbers continues to increase as future eco-friendly building absorbers.

scholarly journals Sound Absorption Coefficient of Different Green Materials Polymer on Noise Reduction

2020 ◽  
Vol 9 (3) ◽  
pp. 2773-2777
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
New Technologies ◽  
Raw Materials ◽  
Agricultural Waste ◽  
Noise Pollution ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Green Materials

One of the sources of noise pollution to environment is from the consumption of electrical and mechanical appliances usage at home and industries. Growth development and advancement of heavy equipment in construction work further emphasize the necessity used of new technologies for noise reduction. The best technique of control or reducing of noise is by using the materials that can absorb the noise by materials itself. Potential materials from agricultural waste as sound absorber were identified. There are two main objectives in this study; First is to produce acoustic absorber by using natural materials. Second is to identify their sound absorption coefficients. The samples were fabricated using the raw materials from banana stem, grass, palm oil leaves and lemongrass mixed with binding agents of polyurethane and hardener to the ratio of 1:4. The diameters of the samples consist of 28mm and 100mm and the thickness is 10mm. The samples sound absorption coefficients were measured according to standards ASTM E1050-98 / ISO 105342-2 (Impedance tube method). Sound absorption coefficient of the materials depends on frequencies choose. The frequencies values used in this study were in the range from 500Hz to 4500Hz. Material made from grass have a higher average sound absorption coefficient value which is 0.553. All tested samples also can be categories under class D type of materials based on sound absorption coefficient value.

Sound Absorption Properties of Fiber and Porous Materials

2005 ◽  
Vol 475-479 ◽  
pp. 2687-2690 ◽  
Author(s):  
Bo Young Hur ◽  
Bu Keoun Park ◽  
Dong-In Ha ◽  
Yong Su Um
Keyword(s):  
Absorption Coefficient ◽  
Porous Materials ◽  
Sound Absorption ◽  
Absorption Rate ◽  
Metal Foam ◽  
Acoustic Property ◽  
Glass Wool ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Reduction Coefficient

The porous materials, such as glass wool or foam, are generally used to attenuate noise. The most fundamental acoustic property of these porous materials is their sound absorption coefficient. The purpose of this paper is sintered fiber and porous materials sound absorption properties investigated. Sound absorption properties of sintered Al fiber has over 0.7 of sound absorption coefficient with 800-2000Hz frequency for 0.6 relative density and 10mm thickness. NRC (noise reduction coefficient) is 0.73. Metal foam have good sound absorption rate at 2000 ~ 4000Hz.

scholarly journals The Sound Absorption Coefficient of Railway Concrete Sleepers Containing Palm Oil Fuel Ash (POFA) As a Cement Replacement Material

2021 ◽  
Vol 2129 (1) ◽  
pp. 012032
Author(s):  
Nurfarhanna Ahmad Sulaiman ◽  
Suraya Hani Adnan ◽  
Abdul Hadi Izaan ◽  
Mohamad Hairi Osman ◽  
Mohamad Luthfi Ahmad Jeni ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Palm Oil ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Palm Oil Fuel Ash ◽  
Noise And Vibration ◽  
Fuel Ash ◽  
Reduction Coefficient ◽  
Oil Fuel

Abstract Major noise and vibration during train operation can cause disturbance to the surrounding. One of the methods to reduce this disturbance are by installing concrete sleepers. The use of railway concrete sleepers may be a high potential to reduce the noise and vibration. To produce concrete sleepers cement usage will be used with greater volume. Approximately 100 million tons of Palm Oil Fuel Ash (POFA) was disposed to the landfill currently. POFA contains high silica content and porous particles which indicated its pozzolanic properties and sound absorption characteristics. Therefore, this study was to determine the sound absorption coefficient of railway concrete sleepers containing POFA as a cement replacement material. Concrete sleepers with a strength grade of 55 and a w/c ratio of 0.35 were prepared in this study. Three design mixes with 0% (control), 20%, and 40% of POFA tested by using an impedance tube test at 28 days of curing age. The results show, the sound absorption coefficient and noise reduction coefficient increases as the percentage of POFA increases. The best performance was obtained by concrete sleepers containing 40% of POFA, with a recorded sound absorption coefficient of 0.10 for low frequency and 0.44 for high frequency. Meanwhile, the noise reduction coefficient recorded was 0.33, which reduce 32% of noise compared to OPC.

scholarly journals Acoustic Properties of Sound Absorber from Modified Polyester with Filler Sodium Bicarbonate

2018 ◽  
Vol 34 (4) ◽  
pp. 2187-2191
Author(s):  
Nasmi Herlina Sari ◽  
Jauhar Fajrin
Keyword(s):  
Absorption Coefficient ◽  
Sodium Bicarbonate ◽  
Acoustic Impedance ◽  
Sound Absorption ◽  
Polyester Resin ◽  
Acoustic Properties ◽  
Acoustic Parameters ◽  
Absorbent Material ◽  
Sound Absorber ◽  
Absorption Performance

The combination of low price, ease of manufacturing and waterproofing characteristics has placed polyester resin as a potential sound absorbent material. Previous studies showed that adding filler material to the blending may increase the acoustics properties of a sound absorbent material. This study aims to investigate the potential of sodium bicarbonate (NaHCO3) to be employed as a filler to improve the acoustic properties of the sound absorber made of polyester resin. Two important acoustic parameters were carefully assessed; absorption coefficient and acoustic impedance. The results showed that the sound absorption performance increased significantly at low and medium frequencies in the presence of NaHCO3 filler in polyester resin. Meanwhile, the use of a back cavity on the absorbent material reduced the sound absorption performance of materials at low and medium frequencies. This suggests that sound absorber made of polyester with sodium bicarbonate filler may be used as an alternative for sound absorber materials.

Effect of microfiber layers on acoustical absorptive properties of nonwoven fabrics

2019 ◽  
Vol 50 (3) ◽  
pp. 312-332 ◽  
Author(s):  
Gajanan Bhat ◽  
Magdi El Messiry
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Decisive Role ◽  
Mineral Wool ◽  
Acoustic Energy ◽  
Sound Absorption Coefficient ◽  
Nonwoven Materials ◽  
Reduction Coefficient ◽  
Melt Blown Nonwoven

There are several types of sound absorptive materials, such as natural and synthetic fibers, acoustic mineral wool, acoustic polyester panels, acoustic foam, cotton batts, that reduce the acoustic energy of a sound wave as the wave passes through. In this work, the use of nonwoven materials made of cotton, polyester, and polypropylene fibers for the development of sound absorptive nonwoven materials has been investigated. Samples of different materials (cotton, cotton/polyester blend, polyester fibers needle punched, and polypropylene melt blown nonwoven) and multilayer structures were tested on the designed impedance tube. Acoustic absorption properties of the fiber assemblies were studied in the frequency region of 100–1500 Hz. The values of sound absorption coefficient for different samples indicated that polypropylene microfiber melt blown nonwoven sample displayed a good sound absorption behavior in the entire frequency range. The use of multilayer samples improves the sound absorption coefficient with the condition that one of the layers is a thin melt blown nonwoven layer. The formation of nonwoven absorbent material consisted of hybrid layers, significantly reduces the resultant average sound absorption coefficient, especially when the upper layer is made from finer fibers of melt blown nonwoven of low air permeability value, and in this case the improvement reaches 50%. The use of melt blown layers of fine fibers values of noise reduction coefficient may reach 0.8. The multilayer nonwoven sound absorber design should take into consideration specific noise reduction coefficient values, not the absolute ones, particularly when the weight of the absorber is playing a decisive role.

Study on Influencing Factors of Noise Reduction Performance of Pervious Concrete

2019 ◽  
Vol 971 ◽  
pp. 106-113
Author(s):  
Ji Liang Wang ◽  
Zi Dong Niu ◽  
Qian Chen ◽  
Yong Yan Yu ◽  
Xiao Chen
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Influencing Factors ◽  
Coating Thickness ◽  
Sound Absorption ◽  
Pervious Concrete ◽  
Absorption Coefficients ◽  
Reduction Function ◽  
Reduction Effect ◽  
Technical Basis

In this experiment, four kinds of pervious concrete with different porosity (10%, 15%, 20%, 25%), four kinds of paste coating thickness (0.3mm, 0.5mm, 0.7mm, 0.9mm) and four kinds of thickness (30mm, 40mm, 50mm, 60mm) were prepared and their sound absorption coefficients under different frequency bands were tested. The results show that with the increase of target porosity, the thickness of paste coating and the thickness of pervious concrete, the sound absorption coefficient of pervious concrete increases firstly and then decreases. Through comprehensive consideration, when the target porosity is 18%, the thickness of paste coating is 0.5mm and the thickness is 40mm, pervious concrete has the best noise reduction effect. It provides a technical basis for the design of pervious concrete with noise reduction function.

scholarly journals Surface Tension Effect on Sound Absorption Characteristics of a Cavity-Backed Semi-Permeable Membrane

2015 ◽  
Vol 773-774 ◽  
pp. 23-27 ◽  
Author(s):  
Muhd Hafeez Zainulabidin ◽  
L.M. Wan ◽  
Al Emran Ismail ◽  
M.Z. Kasron ◽  
A.S.M. Kassim
Keyword(s):  
Surface Tension ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Membrane Surface ◽  
Surface Tension Effect ◽  
Permeable Membrane ◽  
Reduction Coefficient ◽  
Absorption Performance ◽  
Impedance Tube Method ◽  
Absorption Characteristics

This paper describes the analysis on the characteristics of semi-permeable membrane sound absorber. The effects of membrane surface tension on the sound absorption characteristics were investigated. The characteristics of the membrane absorber was measured experimentally in terms of Sound Absorption Coefficient, α and Noise Reduction Coefficient, NRC. The membrane is made of thin, flexible, semi-permeable latex material and the tests were carried out by using impedance tube method according to ISO 10534-2 standard. The results showed that the surface tension has significant influence on the sound absorption characteristics. For the parameters used in the laboratory work, specimen with unstretched surface tension has the best absorption performance.

Effect of Density on the Sound Absorption of Date Palm Fibers

2014 ◽  
Vol 663 ◽  
pp. 437-441 ◽  
Author(s):  
Elwaleed Awad Khidir ◽  
Nik Abdullah Nik Mohamed ◽  
Mohd Jailani Mohd Nor ◽  
Mohd Faizal Mat Tahir ◽  
Rozli Zulkifli ◽  
...  
Keyword(s):  
Experimental Study ◽  
Built Environment ◽  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Date Palm ◽  
Absorption Properties ◽  
Palm Fiber ◽  
Date Palm Fibers ◽  
Reduction Coefficient

An experimental study on the effect of panel density on the sound absorption properties of a date palm fiber panel has been presented in this paper. The experiments were carried out by using impedance tube at the Acoustic Lab, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia. The date palm fiber was tested for densities of 77 kg/m3, 100 kg/m3 and 125 kg/m3.The results show that the values of absorption coefficient improve when increasing the density of the panel. Noise reduction coefficient (NRC) was computed to compare the performance of the palm date fiber samples for the different densities. The NRC increases by increasing the density.

Sound Absorption of Laminated Biopolymer Foam and Epoxy Foam

2013 ◽  
Vol 594-595 ◽  
pp. 291-295 ◽  
Author(s):  
Noor Quratul Aine Adnan ◽  
Anika Zafiah M. Rus
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Vegetable Oil ◽  
Sound Absorption ◽  
Acoustic Property ◽  
Sound Absorption Coefficient ◽  
Behavior Theory ◽  
Tube Test ◽  
Epoxy Foam ◽  
Reduction Coefficient

Biopolymer foam was prepared based on vegetable oil and Polyol Flexible (Epoxy) with commercial Polymethane Polyphenyl Isocyanate (Modified Polymeric-MDI) as laminated foam. The acoustic property of biopolymer foam was examined by impedance tube test according to ASTM E-1050 of sound absorption coefficient (α). From the result obtain, sample D and sample C are the best result of sound absorption coefficient (α) for biopolymer foam and epoxy foam with the value are 0.867 and 0.817 respectively. By using the sound behavior theory, when the thickness is increase the sound absorption is also increase as same as in this study. The noise reduction coefficient (NRC) of sample D is 38.26% while for sample C is 37.42%.

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