scholarly journals A Re‐Examination of the Noise Reduction Coefficient

1941 ◽  
Vol 13 (1) ◽  
pp. 83-83 ◽  
Author(s):  
J. S. Parkinson ◽  
W. A. Jack
Keyword(s):  
Noise Reduction ◽  
Reduction Coefficient

A Re‐Examination of the Noise Reduction Coefficient

1941 ◽  
Vol 13 (2) ◽  
pp. 163-169 ◽  
Author(s):  
J. S. Parkinson ◽  
W. A. Jack
Keyword(s):  
Noise Reduction ◽  
Reduction Coefficient

scholarly journals Pembuatan Sistem Perancang Peredam Kebisingan

2020 ◽  
Vol 4 (2) ◽  
pp. 56-64
Author(s):  
Rahmat Bagus Prasetya ◽  
Sunartoto Gunadi ◽  
Erna Kusuma Wati
Keyword(s):  
Data Collection ◽  
Noise Reduction ◽  
Transmission Coefficient ◽  
Loss Factor ◽  
Measurement Method ◽  
Sound Transmission ◽  
Reduction Coefficient ◽  
Noise Measurements ◽  
At Home

One of the problems experienced by the community, whether at home or at work, was the disruption in the sense of concentration caused by noise. This study aims to measure noise as well as provide materials to reduce noise in the area. The time for data collection was one day, carried out for 4 samples of data collection based on a reference from the Ministry of Environment, no: Kep-48 / MENLH / 11/1996. The measurement method also using SNI standard number 7231 in 2009. Then based on the noise value displayed on the instrument, material recommendations will be given based on the value of Noise Reduction Coefficient (NRC), Sound Transmission Coefficient (STC) and Loss Factor. The results of noise measurements at the AT-Taqwa Mosque are 77.1 dB and the recommended material recommended by the tool is Acourete Perfowood - Acoustic Panel 881 with NRC 0.375. While the measurement at the Musholla at Pasar Minggu station is 76.8 dB and the recommended material recommended by the tool is Accourete Fiber 300 with an NRC of 0.44.

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 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 Sound Performances of Partition Board from Waste Materials

2021 ◽  
Vol 920 (1) ◽  
pp. 012011
Author(s):  
U Kassim ◽  
S A Nur ◽  
M N Kamarudin ◽  
M A Rahim
Keyword(s):  
Noise Reduction ◽  
High Intensity ◽  
High Frequency ◽  
Low Frequency ◽  
Test Point ◽  
Sound Level ◽  
Waste Materials ◽  
Horizontal Line ◽  
Low Intensity ◽  
Reduction Coefficient

Abstract This study is on the sound performances of a selected number of partition boards in Industrialised Building System (IBS) buildings. The proposed bespoke board were made from squandered or waste materials, namely, coconut shells and newspapers. Each board had been tested for six different distances from the speaker in four different levels of sound, changing the level of the sound frequency. Thereon, the results were analysed. The average result of each board with various distances from the sound source, starting from 0 cm to 220 cm, was combined into under one sound level. The percentage of the noise reduction coefficient is designated by the vertical line whereas the levels of the sound is designated by the horizontal line. Point 1 stands for the low frequency and low intensity test. Point 2 stands for low frequency and high intensity test. The board that is being made of 80% coconut shell, 15% cement and 5% newspaper has an average of noise reduction coefficient of 0.21 in low frequency and low intensity, 0.21 in low frequency and high intensity, 0.24 in high frequency, high intensity and 0.12 in high frequency low intensity.

Investigation of Noise Reduction Coefficient of Organic Material as Indoor Noise Reduction Panel

2014 ◽  
Vol 803 ◽  
pp. 317-324 ◽  
Author(s):  
Tengku Nuraiti Tengku Izhar ◽  
Laila Mardiah Deraman ◽  
Wani Nadirah Ibrahim ◽  
Nabilah Aminah Lutpi
Keyword(s):  
Noise Reduction ◽  
Rice Husk ◽  
Organic Material ◽  
Noise Level ◽  
Polyester Resin ◽  
Coir Fiber ◽  
Wall Surface ◽  
Reduction Coefficient ◽  
Coconut Coir ◽  
Sound Reduction

Noise can cause a few types of effect to human health especially in hearing like hearing loss. Indoor noise pollution comes from many sources and places. The research focuses on the sound reduction wall surface material rather than any techniques available and using organic material like coconut coir fiber, rice husk and sawdust. These sound reduction material is suitable to apply as interior lining for homes and offices. This research conducted to compare the efficiency of coconut coir fiber, rice husk and sawdust as indoor noise reduction, to evaluate the effectiveness indoor noise level by using wall surface sound reducer material and to determine the best material that will reduce noise level. In preparation of board panel, two binders were used which is polyester resin and hardening catalyst, cement and sand. For board panel using binder of polyester resin and hardening catalyst, the binders were stirred for two minutes. Then, the mixture of polyester resin, hardening catalyst with raw material was mix uniformly. The suppression done for 24 hours in order to obtain a composite outcome that is denser. Then, the ratio for coconut coir fiber, cement and sand is 1.5:0.5:0.5, the same ratio used for sawdust and rice husk and the Noise Reduction Coefficient (NRC) will be determined. The parameter use to determine the NRC and the sound transmission are the frequency, speaker intensity and the distance from the speaker. If not absorbed, the sound can be reflected and this will prevent sound dispersed to other space. The results show rice husk is better with cement binder and sand, while for polyester resin and hardening catalyst binder, sawdust is the best. Therefore, currently organic materials present good alternative to synthetic material providing good health with green environment as well as enhancing natural agricultural and growth.

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.

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 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.

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