Effect of Bulk Density on the Acoustic Performance of Thermally Bonded Nonwovens

2015 ◽  
Vol 10 (3) ◽  
pp. 155892501501000 ◽  
Author(s):  
Wenbin Zhu ◽  
Vidya Nandikolla ◽  
Brian George
Keyword(s):  
Absorption Coefficient ◽  
Bulk Density ◽  
Sound Absorption ◽  
Flow Resistance ◽  
Raw Materials ◽  
Sound Absorption Coefficient ◽  
Acoustic Performance ◽  
Materials Used ◽  
Lower Bulk Density ◽  
Blend Ratios

The effect of different fiber blend ratios and bulk densities at similar thicknesses on air permeability and sound absorption coefficient was investigated. The raw materials used were cotton, polyester, and bi-component fibers to make acoustic nonwovens through the air-laid and thermal bonding processes. A uniform thermal-conductivity box was designed in order to make thermally bonded nonwovens with fixed thicknesses. The experimental results depict that the air flow resistance of three-layer nonwoven was 0.565 kPa&mitdott;s/m, which was about four times greater than one-layer of 0.12 kPa·s/m. Sound absorption coefficient of 20% polyester-60% cotton-20% bicomponent nonwoven with lower bulk density was greater than the 60% polyester-20% cotton-20% bicomponent nonwoven. The sound absorption coefficient varied based on which fabric side faced the testing apparatus.

scholarly journals Sound Absorption Performance of Sugar Palm Trunk Fibers

2019 ◽  
Vol 130 ◽  
pp. 01003
Author(s):  
Anditya Endar Prabowo ◽  
Kuncoro Diharjo ◽  
Ubaidillah ◽  
Iwan Prasetiyo
Keyword(s):  
Absorption Coefficient ◽  
Bulk Density ◽  
Sound Absorption ◽  
Random Noise ◽  
Air Gap ◽  
Sound Absorption Coefficient ◽  
Low Frequencies ◽  
Central Java ◽  
Absorption Performance ◽  
Small Medium Enterprises

The purpose of this research is to investigate the effect of bulk density, thickness, and air gap to sound absorption performance on absorber based sugar palm trunk fibers. The fibers were obtained from solid waste on Small-Medium Enterprises of sago flour processing in Klaten, Central Java, Indonesia. The absorber specimens were formed from the fibers using a simple press molding in an oven at 150 °C. According to ISO 10534-2, the absorber samples were tested using two microphones impedance tube with random noise source to get the curve of the sound absorption coefficient. The result shows that the absorption performance can be improved by increasing bulk density and increasing of sample thickness. Especially at low frequencies, improvement of the sound absorption coefficient can be achieved (NAC > 0.8) by applying the air gap behind the sample. The best performance of absorber based sugar palm trunk fiber can be achieved for (1 000 to 6 000) Hz range frequency.

scholarly journals Analisis Koefisien Serapan (Absorbsi) kebisingan pada Bahan Kayu (Triplek, Papan Kayu dan Kalsiboard)

2021 ◽  
Vol 2 (1) ◽  
pp. 19
Author(s):  
Siti Istikhomah ◽  
Syahrir Syahrir ◽  
Adrianus Inu Natalisanto
Keyword(s):  
Absorption Coefficient ◽  
Environmental Factor ◽  
Sound Absorption ◽  
Active Material ◽  
Sound Absorption Coefficient ◽  
Noise Levels ◽  
Research Results ◽  
Its Analysis ◽  
Wood Panels ◽  
Materials Used

Noise is a sound that humans do not want and it is an environmental factor that can negatively affect health. To overcome the noise issue, many efforts have been made to reduce noise levels. An example is the manufacture of the walls of a house using materials with sound and absorbent standards. The materials used can also be derived from types of wood such as plywood, wood panels and calciboards. Therefore, the value of its sound absorption coefficient is calculated to find out which active material is to be used in the manufacture of the building. Based on the research results, the value of the sound absorption coefficient of the three types of materials, it can be seen that the shape of the graph and its analysis states that the lowest sound absorption coefficient is most likely at the lower frequencies and the highest value of the sound absorption coefficient tends to be at the higher frequencies. In fact, when viewed as a whole, the magnitude and magnitude of the sound absorption coefficient on the graph is not in line with the increase in the frequency value.

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.

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.

A study on the effects of compression of the felt on flow resistance and acoustic characteristics

2021 ◽  
Vol 263 (1) ◽  
pp. 5170-5174
Author(s):  
Yoon-sang Yang ◽  
Seung Lee
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Flow Resistance ◽  
Transmission Loss ◽  
Combustion Engine ◽  
Characteristic Impedance ◽  
Sound Transmission ◽  
Sound Absorption Coefficient ◽  
Sound Transmission Loss ◽  
Acoustic Characteristics

The sound absorbing materials used to reduce automobile interior noise are classified into Felt and PU Foam. Felt are widely used not only in internal combustion engine vehicles but also in Electric Vehicles because they are eco-friendly materials that can be recycled and relatively light. Automotive interior parts manufacture materials in various thicknesses depending on the shape of matched parts. The pressed material changes the density, flow resistance and affects the overall NVH performance of the vehicle. In this study we worked to confirm changes in flow resistance, sound absorption coefficient and sound transmission loss performance among acoustic characteristics based on the compress ratio of Felt. It was confirmed that the larger the compression of Felt, the larger the flow resistance value, thereby affecting the acoustic characteristic impedance, sound absorption coefficient and sound transmission loss.

SOUND ABSORPTION ON BOARD CONSTRUCTION MATERIALs USED IN WOOD BUILDINGS

Akustika ◽  
2020 ◽  
pp. 51-57
Author(s):  
Martin Čulík ◽  
Anna Danihelová ◽  
Vojtěch Ondrejka ◽  
Patrik Aláč
Keyword(s):  
Absorption Coefficient ◽  
Sound Wave ◽  
Sound Absorption ◽  
Oriented Strand Board ◽  
Construction Materials ◽  
Sound Absorption Coefficient ◽  
Frequency Interval ◽  
Low Energy Buildings ◽  
Materials Used ◽  
Enclosed Space

When the sound wave touches the material (wall), some fraction reflex the wall, other fraction is absorbed and the rest fraction of the sound wave will go through the wall. So, in every enclosed space we can say about sound absorption, transformation of sound energy into some other energy. Sound absorption coefficient α (-) can be mentioned as criteria for the standard of sound absorption by the material. The article deals with the evaluation of sound absorption in the chosen materials which are utilised in wooden buildings, construction parts of partition walls and ceilings, floors and walls cover. There were used the following materials which are applied in the construction of wood buildings: particleboard (DTD), oriented strand board (OSB), beech plywood (PDP_BK), poplar plywood (PDP_TO), tetra pak recycled board (TETRA K), gypsum fibreboard (Fermacell), cement chipboard (CTD), plasterboard (Rigips) and medium-density fibreboard (MDF). The measurement was performed by the transfer function method in accordance with the standard ISO 10534-2. Under the frequency in the range 200 Hz – 2.0 kHz, the highest values of sound absorption coefficient were measured in CTD, PDP_TO, DTD and OSB within the interval from 0.05 to 0.53. Fermacell and Rigips have the highest values of sound absorption coefficient (0.3 – 0.4) within the frequency from 2.5 kHz to 4 kHz. At the same time, Fermacell, Rigips, but also MDF and TETRA K boards reached the lowest sound absorption (0 – 0.21) within the frequency interval 50 Hz – 2.0 kHz. Sound absorption assessed on the base of NRC coefficient was measured as very low (under 0.2) for all assessed materials, except of CTD. The tested board materials according to the standard ISO 11654 can be included among sound reflective material and little sound absorptive material. The highest level of noise reduction coefficient αNRC was measured at cement chipboard CTD (αNRC = 0.3) which can be included among absorptive materials. The results should be transformed into predictions in room and building acoustics, particularly in the design and projection of partition wall constructions in ultra-low energy buildings but also in the entire interior equipment.

Influence of Spheroid and Fiber-Like Waste-Tire Rubbers on the Sound Absorption Coefficient of Rubberized Mortars

2019 ◽  
Vol 958 ◽  
pp. 63-68
Author(s):  
Edson Jansen Pedrosa Miranda Jr. ◽  
Andressa Fernanda Angelin ◽  
S.F. Rodrigues ◽  
Luísa Andréia Gachet-Barbosa ◽  
J.M.C. dos Santos
Keyword(s):  
Transfer Function ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Function Method ◽  
Sound Absorption Coefficient ◽  
Experimental Characterization ◽  
Acoustic Performance ◽  
Waste Tire ◽  
Transfer Function Method ◽  
Rubber Particles

We study the sound absorption coefficient of rubberized mortars in response to the incorporation of 7.5%, 15% and 30% of waste-tire rubbers in place of sand at a water-to-cement mass (w/c) ratio of 0.48. We consider two different morphologies of rubber particles, namely spheroid (S) and fiber-like (F) particles. Experimental characterization was performed after 7 days of curing. The mixtures were performed by density, water absorption, void index and sound absorption. We choose the transfer function method with one microphone successively in two locations in order to obtain the sound absorption coefficient using an impedance tube. Sound absorption coefficient results indicate a slightly enhancement for 7.5% S, 15% S, 30% S and 7.5% F mixtures from 1600 Hz to 2000 Hz. The best acoustic performance is observed for 30% S and 7.5% F mixtures from 850 Hz to 2000 Hz.

scholarly journals Potensi Sekam Padi dan Jerami sebagai Alternatif Material Akustik

2020 ◽  
Vol 2 (1) ◽  
pp. 35
Author(s):  
Ahmad Minanur Rohim ◽  
Fianti Fianti ◽  
Upik Nurbaiti
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Measuring Instrument ◽  
Test Results ◽  
Sample Material ◽  
Information Communication ◽  
Rice Husks ◽  
Materials Used ◽  
Cylindrical Samples

<p class="Abstract">Technology that is increasingly developing produces equipments in the form of information, communication, production, transportation and entertainment facilities. Most of the equipments produce noises. Noise can be reduced by using acoustic dampers. This study aims to determine the potential for sound absorption from rice husks and straw as natural acoustic materials. Materials used include rice husks, rice straw, and resin. 12 cylindrical samples were made. Samples that have been made are tested using a sound absorption measuring instrument that is the impedance tube to measure the value of the sample sound absorption coefficient. The test results show the value of the sound absorption coefficient (α) can be influenced by the thickness. At a frequency of 500 Hz the value of the sound absorption coefficient (α) for each sample is 0.034dB; 0.030dB; 0.030dB; 0.027dB; 0.026dB; 0.027dB; 0.025dB; 0.025dB; 0.025dB; 0.024dB; 0.024dB; 0.023dB; 0.023dB. The sample material is good in research on materials 1 and 2 which have a sound absorption of 0.034 dB and 0.030 dB.</p>

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