Spaced object absorbers, sound absorption coefficients, and the noise reduction coefficient rating in architecture

2021 ◽  
Vol 150 (4) ◽  
pp. A117-A117
Author(s):  
Eric P. Wolfram
Keyword(s):  
Noise Reduction ◽  
Sound Absorption ◽  
Absorption Coefficients ◽  
Reduction Coefficient

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 Crumb Rubber Effect on Acoustic Properties of Self- Consolidating Concrete

2014 ◽  
Vol 08 (2) ◽  
Keyword(s):  
Experimental Study ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Crumb Rubber ◽  
The Self ◽  
Acoustic Properties ◽  
Scrap Tires ◽  
Self Consolidating Concrete ◽  
Reduction Coefficient ◽  
Environmentally Sound

Several researches have been conducted to find a practical and environmentally sound solution of the problem of scrap tires. In this context, an experimental study was conducted to provide more data on the effect of crumb rubber on the acoustic properties of self-consolidating concrete SCC. To this end, Parallelepiped and cylindrical specimens were prepared by varying the proportion of crumb rubber with percentages of 0 %, 10 %, 20 % and 30 % of the volume of gravel. Properties such standardized level difference, sound absorption at different frequency and noise reduction were investigated. The results showed that the sound absorption and noise reduction coefficient were increased according to the increase of the percentage of crumb rubber. The self-consolidating concrete rubber SCCR has better acoustic properties in comparison with SCC.

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.

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.

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 Delignification Effects on Indonesian Momala (Homalium foetidum) and Korean Red Toon (Toona sinensis) Hardwood Pore Structure and Sound Absorption Capabilities

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5215
Author(s):  
Eun-Suk Jang ◽  
Chun-Won Kang
Keyword(s):  
Pore Structure ◽  
Noise Reduction ◽  
Pore Size ◽  
Sound Absorption ◽  
Gas Permeability ◽  
Air Gap ◽  
Toona Sinensis ◽  
Reduction Coefficient

Among the various methods used to improve the sound absorption capability of wood, we focused on delignification in Indonesian momala (Homalium foetidum) and Korean red toon (Toona sinensis). We performed gas permeability, pore size, and porosity analyses and evaluated how the change in the pore structure affects the sound absorption capabilities. Results show that delignification increased the through-pore porosity and improved sound absorption capability in both species. In addition, the air gap in the rear space maximized the sound absorption of momala and the red toon. The noise reduction coefficient (NRC) of delignified momala (90 min) with a 3 cm air gap was 0.359 ± 0.023. This is approximately 154.6% higher than that of untreated momala without an air gap. The NRC of delignificated red toon (90 min) with a 3 cm air gap was 0.324 ± 0.040, an increase of 604.3% over untreated red toon without an air gap.

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%.

Development of Kenaf Nonwoven as Automotive Noise Absorption

2019 ◽  
Vol 892 ◽  
pp. 101-105
Author(s):  
Siti Nor Hawanis Husain ◽  
Nur Aiman Abdul Razak ◽  
Azrin Hani Abdul Rashid ◽  
Musli Nizam Bin Yahya ◽  
Nurul Zakiah Zamri Tan ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Negative Relationship ◽  
Sound Absorption Coefficient ◽  
Function Technique ◽  
Impedance Tube ◽  
Number Of Layers ◽  
Reduction Coefficient ◽  
Sound Reduction

Getting rid of unwanted noise in car compartment is necessary and really significant measure for automotive makers. This research was directed to produce nonwoven material from Kenaf fiber using the needle-punching machine and the ability of the produced material to absorb sound will be tested. The performance in sound absorption of the sample was analyzed by the sound absorption coefficient (SAC) and noise reduction coefficient (NRC) using the impedance tube test referring to ASTM E1050-98. The sound absorption frequencies were evaluated utilizing the two-microphone transfer function technique in the impedance tube that has a 100 mm diameter for low frequency and 28 mm for high frequency, 0 Hz to 4000 Hz respectively. The physical examination also was executed according to ASTM D1772 to determine the density and the thickness of each sample. The parameter verified in this research is the number of layers to form the samples and it also were compared with the commercial products. As the outcome of this research, the sound absorption coefficient (SAC) showed that the sound reduction coefficient value was increased as the number of layers of the sample increase. In summation, the result also proved that the denser the samples, the higher the absorption coefficient value. On the other hand, for the noise reduction coefficient (NRC), overall result showed slight differences between each sample. The result is due to the rating is an average, two materials with the same rating might not perform the same. Referring to the previous research, the sample with higher areal density is dependable for higher sound reduction and there is a negative relationship between area density and bulk density of needle-punched nonwoven and sound reduction. With the rise in the number of density of nonwoven fabric, the sound reduction through the fabric increases at first but after the maximum it remains almost unaffected.

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