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.

The Sound Absorption Properties Comparison of Metal Foams and Flexible Cellular Materials

2018 ◽  
Vol 933 ◽  
pp. 357-366 ◽  
Author(s):  
Li Si Liang ◽  
Xiao Lei Wu ◽  
Na Ni Ma ◽  
Jin Jing Du ◽  
Man Bo Liu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Metal Foam ◽  
Metal Foams ◽  
Cellular Materials ◽  
Glass Wool ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Average Value ◽  
Peak Value

The third octave sound absorption coefficient testing is conducted to compare the sound absorption properties metal foam and flexible cellular materials, by using sound absorption tester with the method of trasfer function sound absorption tester with the method of trasfer function. The sound absorption mechanisms are discussed by changing the parameters of sound absorption structure, such as the thickness of matrix materials and the thickness of cavity. The results show that pearl wool and glass wool exhibited excellent sound absorption properties. The peak value of sound absorption coefficient for pearl wool reaches to 0.991, and for glass wool, 0.985. The average sound absorption coefficient for pearl wool is 0.729, and for glass wool, 0.679. Among of three metal foams, the foamed aluminum material exhibited optimum sound absorption properties, and is superior to flexible sound absorption materials. The peak value of sound absorption coefficient reaches to 0.993, and the average value reaches to 0.781. This can be attributed to the flow resistance, porosity, thickness, cavity and structure factor, which influence the sound absorption of open cell materials.

Fabrication and Sound Absorption Properties of Porous Fe0.2(Co20Ni80)0.8 Alloy Microfibers

2012 ◽  
Vol 538-541 ◽  
pp. 2220-2223
Author(s):  
Xiang Qian Shen ◽  
Hong Bo Liu ◽  
Qing Rong Liang ◽  
Xin Chun Yang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transformation Process ◽  
Sound Absorption Coefficient ◽  
Wave Tube ◽  
Absorption Properties ◽  
Thick Sample ◽  
Noise Absorption ◽  
Reduction Coefficient ◽  
Standing Wave Tube

The porous nanocrystalline Fe0.2(Co20Ni80)0.8 alloy microfibers with diameters of 2-4 μm have been prepared by the citrate-gel and phase transformation process. The sound absorption coefficient for microfibers samples is measured by the standing wave tube method and it is is over 0.8 for the 15 mm thick sample at the frequency range of 2300-6000 Hz, which is extended to 600-6300 Hz for the 40 mm thick sample. The band width with the sound absorption coefficient above 0.6 is wider than 4300 Hz for the 15 mm thick sample and 5800 Hz for the 40 mm thick sample. For the 40 mm thick sample, the maximum absorption coefficient, noise absorption coefficient, noise reduction coefficient and half-width of the absorption peak are 0.99, 0.59, 0.64 and 5828 Hz, respectively. These microfibers are promising advanced acoustic absorbers.

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%.

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).

Physical and Sound Absorption Properties of Spent Tea Leaf Fiber Filled Polyurethane Foam Composite

2014 ◽  
Vol 660 ◽  
pp. 541-546 ◽  
Author(s):  
Qumrul Ahsan ◽  
Chia Pooi Ching ◽  
Mohd Yuhazri bin Yaakob
Keyword(s):  
Absorption Coefficient ◽  
Polyurethane Foam ◽  
High Resistance ◽  
Sound Absorption ◽  
Filler Loading ◽  
Tea Plant ◽  
Sound Absorption Coefficient ◽  
Tea Leaves ◽  
Absorption Properties ◽  
Spent Tea Leaves

Spent tea leaves (STL) from tea producing factories can be considered as new resources for sound absorbing polyurethane (PU) matrix composite materials because STL are rich in polyphenols (tannins) which cause high durability, high resistance to fungal and termites, and high resistance to fire. The research aims to study the physical characteristics of STL and the effect of dispersion morphology of STL on the sound absorption properties of polyurethane foam composites by varying filler loading. Three grades of STL fibers either as received or granulated are used in this study, namely BM-FAE and SWBHE derived from the stalk while FIBER-FAE derived from the leaves of the tea plant. The PU/STL composites are fabricated through open molding method with a fiber loading of 16 wt. %. The fabricated composites are then subjected to physical and sound absorption testing as well as microscopic observations to analyze the distribution of filler in composite. The study shows that as-received FIBER-FAE spent tea leaves provide the best sound absorption coefficient and for composites using granulated fibers from any grade have lower sound absorption coefficient. These results show that a novel kind of sound absorption materials with the recycling of waste materials can be obtained for the solution of noise and environmental pollution.

scholarly journals Sound absorption properties of multi-layer structural composite materials based on waste corn husk fibers

2020 ◽  
Vol 15 ◽  
pp. 155892502091086
Author(s):  
Lihua Lyu ◽  
Jing Lu ◽  
Jing Guo ◽  
Yongfang Qian ◽  
Hong Li ◽  
...  
Keyword(s):  
Composite Materials ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Low Frequency ◽  
Sound Absorption Coefficient ◽  
Absorption Properties ◽  
Cavity Depth ◽  
Air Cavity ◽  
Corn Husk ◽  
Structural Composite

In order to find a reasonable way to use the waste corn husk, waste degummed corn husk fibers were used as reinforcing material in one type of composite material. And polylactic acid particles were used as matrix material. The composite materials were prepared by mixing and hot-pressing process, and they were processed into the micro-slit panel. Then, the multi-layer structural sound absorption composite materials were prepared sequentially by micro-slit panel, air cavity, and flax felt. Finally, the sound absorption properties of the multi-layer structural composite materials were studied by changing flax felt thickness, air cavity depth, slit rate, and thickness of micro-slit panel. As the flax felt thickness varied from 0 to 10 mm in 5 mm increments, the peak of sound absorption coefficient shifted to low frequency. The sound absorption coefficient in the low frequency was improved with the air cavity depth varied from 0 to 10 mm in 5 mm increments. With the slit rate increased from 3% to 7% in 2% increments, the peak of sound absorption coefficient shifted to high frequency. With the thickness of micro-slit panel increased from 2 to 6 mm in 2 mm increments, the sound absorption bandwidth was broaden, and the peak of sound absorption coefficient was increased and shifted to low frequency. Results showed that the highest sound absorption coefficient of the multi-layer structural composite materials was about 1 under the optimal process conditions.

Acoustic Benefits of Ecofriendly Spent Tea Leaves Filled Porous Material

2017 ◽  
Vol 739 ◽  
pp. 125-134
Author(s):  
Kylie Wong ◽  
Qumrul Ahsan ◽  
Azma Putra ◽  
Sivarao Subramonian ◽  
Noraiham Mohamad ◽  
...  
Keyword(s):  
Absorption Coefficient ◽  
High Resistance ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Acoustic Property ◽  
Tea Plant ◽  
Sound Absorption Coefficient ◽  
Acoustic Performance ◽  
Absorbing Material ◽  
Tea Leaf

This paper demonstrates the feasibility of spent tea leaf (STL) fiber as an eco-friendly sound absorbing material. STL fiber is a by-product which was extracted from tea plant. STL are rich in polyphenols (tannins) which cause high resistance to fungal and termites, and high resistance to fire. In addition, STL are hollow and cellular in nature and thus perform well as acoustic and thermal insulators. Three different grades of STL were studied and the acoustic property was analyzed in terms of sound absorption coefficient and transmission loss. Experimental measurements of sound absorption coefficient in impedance tube are conducted. It was found that finest STL fiber grade exhibits better acoustic performance among others. Furthermore, the effect of latex binder on the acoustic property of STL fiber was also analyzed. Results suggest that the types of binder such as polyurethane and latex influenced the acoustic performance of STL fiber.

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.

Sign in / Sign up

Export Citation Format

Share Document