scholarly journals The Acoustical Characteristics Analysis on Different Type of Natural Fibres

2015 ◽  
Vol 773-774 ◽  
pp. 242-246
Author(s):  
Mathan Sambu ◽  
Musli Nizam Yahya ◽  
Hanif Abdul Latif ◽  
Mohamed Nasrul Mohamed Hatta ◽  
Mohd Imran bin Ghazali
Keyword(s):  
Sound Absorption ◽  
Good Health ◽  
Good Alternative ◽  
Hibiscus Cannabinus ◽  
Natural Fibres ◽  
Optimum Level ◽  
Frequency Range ◽  
Coir Fibre ◽  
Characteristics Analysis ◽  
Coconut Coir

Natural fibres are fibre that can be directly obtained from an animal, mineral, or vegetable sources. Recently natural materials are becoming a good alternative for synthetic material as they provide good health to a greener environment. This aim of this study to investigate and compared the acoustic characteristics of three natural fibres; Kenaf fibre(Hibiscus Cannabinus), Ijuk fibre(Arenga Pinnata), and Coconut coir fibre, where each material is qualified for acoustical absorption. During the processing stage, each fibre is reinforced with 60:40 ratio of pure latex separately. The fibres are then compressed after the pure latex treatment into circular samples, of 28 mm and 100 mm diameters respectively. The thickness of each sample is fixed at 50mm. The acoustical performances were evaluated by using an impedance tube instrument. This study also investigates the effect of air gap of 10mm and 50mm in the sound absorption performance. The results show that, all the three fibres have reached an optimum level of sound absorption value of more than 0.7. The frequency peak value of Kenaf is obtained in a range of 700 Hz – 800 Hz, while for coconut coir is at 1000 Hz – 1075 Hz frequency range. Only Ijuk has obtained the highest frequency range of 3200 Hz – 3400 Hz. The results demonstrate that these three fibres are a promising light and environment-friendly sound absorption material as they are ready to replace the common synthetic fibre.

Sound Absorption Characteristics of Composite Panel Made from Coconut Coir and Oil Palm Empty Fruit Bunches Fibre with Polyester

2021 ◽  
Vol 18 (3) ◽  
pp. 9022-9028
Author(s):  
M. Rusli ◽  
R.S. Nanda ◽  
H. Dahlan ◽  
M. Bur ◽  
M. Okuma
Keyword(s):  
Absorption Coefficient ◽  
Oil Palm ◽  
Sound Absorption ◽  
Natural Fibre ◽  
Composite Panel ◽  
Frequency Range ◽  
Empty Fruit Bunches ◽  
Coir Fibre ◽  
Coconut Coir ◽  
Absorption Characteristics

The development of pure natural fibres as sound absorptive material remains overlooked due to their lack of mechanical and moist properties, low durability, and vulnerability to be damaged by the environment. Certain fibre treatments are needed to improve such disadvantages. This paper investigates sound absorption characteristics of coconut fibre (coir) and oil palm fibre made from empty fruit bunches (OPEFB) fibre bonded by polyester that can protect them from the ambient environment in order to increase their durability. Two types of fibre-polyester composites have been tested. The first is the fibre-polyester composite (FPC) type, which is totally coated with polyester as the composite matrix. Another type is the fibre-polyester bonded composite (FPBC), in which the polyester is brushed into slice by a slice of the fibre layer in order to coat and bond the fibre, although porous among the fibre remains possible. A two-channel impedance tube is used in the measurement within 200 Hz to 3000 Hz of the frequency range. It is found that FPBC type panel has almost similar sound absorption characteristics to its purely natural fibre as it is able to maintain the panel porosity. The coconut coir fibre panel and its composite have a maximum absorption coefficient of almost 100% within the frequency range 1500-2000 Hz, considerably better than the OPEFB fibre, with only about 80% of the absorption coefficient. If the FPC layer exists, the sound absorption is reduced, and the frequency peaks are also shifted. Additions of the FPC panel layer thickness produced lower sound absorptions and shifted the peaks to the lower frequency range. The FPBC panel type is viable to protect the fibre from the environment without changing its sound absorption characteristics.

scholarly journals Acoustic Properties of Mixing Empty Fruit Bunch and Oil Palm Frond Natural Fibres

2019 ◽  
Vol 8 (4) ◽  
pp. 6347-6349
Keyword(s):  
Oil Palm ◽  
Sound Absorption ◽  
Natural Fibre ◽  
Natural Fibres ◽  
Acoustic Properties ◽  
Empty Fruit Bunch ◽  
Frequency Range ◽  
Oil Palm Frond ◽  
Impedance Tube Method ◽  
Palm Frond

Natural fibre is being studied and used as sound absorber for its promising acoustic properties. For instance, Germany have commercial plants that are producing sound absorbers from natural fibre. Natural fibre is eco-friendly and has no effect on human health. Besides that, the production cost of natural fibre is cheaper than synthetic fibre. This research reported the thickness effects on acoustic properties in different ratios of natural fibres of empty fruit bunch (EFB) and oil palm frond (OPF). Four different thickness of low density fibre board (LDF) have been fabricated (12 mm, 14 mm, 16 mm and 18 mm) in density of 120 kg/m3 . The Sound Absorption Coefficient (SAC) was tested by using the Impedance Tube Method (ITM) according to ASTM E1050-98 standards at frequency from 0 Hz to 6400 Hz. The results show the values of SAC for all samples increase with increasing in thickness from frequency range of 0 Hz – 4500 Hz. It is noteworthy that the LDF with thickness of 16 mm and 18 mm can be classified as Class A sound absorbing material according to sound absorption classes and possess the SAC values of 0.8 and above at a wider frequency range, which is 2500 Hz to 6400 Hz. The combination of EFP and OPF natural fibres has a very promising and excellent performance in acoustic properties.

Pekali Penyerapan Bunyi Dan Indek Kehilangan Penghantaran Panel Penyerap Bunyi Menggunakan Gentian Sabut Kelapa

2012 ◽  
Author(s):  
Rosli Zulkifli ◽  
Mohd Faizal Mat Tahir ◽  
Ahmad Rasdan Ismail
Keyword(s):  
Absorption Coefficient ◽  
Oil Palm ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Frequency Range ◽  
Coir Fibre ◽  
Noise Absorption ◽  
Loss Index ◽  
Oil Palm Fibre ◽  
Palm Fibre

Kajian ini dilakukan untuk menentukan sifat akustik panel penyerap bunyi yang di rekabentuk menggunakan bahan gentian sabut kelapa melalui ujikaji dan simulasi. Perbandingan nilai pekali penyerapan bunyi antara bahan gentian sabut kelapa asli dan sabut kelapa yang dimasukkan kedalam panel komposit berlubang telah dibuat. Lapisan luar panel difabrikasi menggunakan panel komposit gentian asli/poliester manakala sabut kelapa terawat digunakan sebagai bahan penyerap bunyi. Panel diuji menggunakan piawaian ISO 354 bagi ujikaji pekali penyerapan bunyi manakala simulasi dijalankan menggunakan perisian WinFLAGTM. Ujian indek kehilangan penghantaran bagi panel penyerap bunyi menggunakan sabut kelapa telah dijalankan dan perbandingan dengan gentian kelapa sawit telah dibuat. Bagi ujikaji pengukuran indek kehilangan penghantaran, Piawaian ISO 717–1 telah digunakan sebagai piawaian. Bagi pekali penyerapan bunyi, hasil eksperimen memberikan nilai penyerapan di antara 0.70 dan 0.80 untuk julat frekuensi dari 1000 Hz sehingga 1800 Hz manakala nilai pekali yang diperoleh dari simulasi pula adalah 0.7 sehingga 0.85 bagi frekuensi berjulat 500 Hz sehingga 2500 Hz. Untuk ujian kehilangan penghantaran, purata indeks kehilangan penghantaran yang dicatatkan adalah 20 dB untuk panel yang mengandungi sabut kelapa dan 17 db untuk panel yang mengandungi gentian kelapa sawit. Hasil keputusan menunjukkan pekali penyerapan bunyi yang diperoleh melalui kaedah eksperimen dan simulasi memberikan nilai yang boleh dianggap baik dan setanding dengan bahan penyerap komersial di pasaran seperti gentian sintetik dan tatal batuan. Indeks kehilangan penghantaran bagi panel yang gentian sabut kelapa pula adalah lebih baik berbanding panel yang mengandungi gentian kelapa sawit. Kata kunci: Bahan akustik; sabut kelapa; pekali penyerapan bunyi; indek kehilangan penghantaran; bilik gema This study was carried out to determine the acoustic properties of a noise absorption panel that was designed to use a coir fibre as noise absorption materials through experimental test and simulation. Comparison of noise absorption coefficient between natural coir fibre and coir fibre inserted inside a perforated panel have been carried out. The outer layer of the panel was fabricated using a coir fibre/polyester composites and treated coir fibre was used as absorption materials. The panel has been tested using ISO 354 standard for noise absorption coefficient while the simulation was carried out using WinFLAGTM software. The transmission loss index test for panel using coir fibre has been carried out and the results was compared with panel using an oil palm fibre. For the transmission loss index, ISO standard 717–1 was used. Experimental results for the noise absorption coefficient give coefficient values between 0.70 and 0.80 for frequency range of 1000 Hz to 1800 Hz while the results from simulation give a coefficient between 0.7 to 0.85 for frequency range of 500 Hz to 2500 Hz. For the transmission loss test, average transmission loss recorded was 20 dB for the panel using coir fibre and 17 dB for panel using an oil palm fibre. Results obtained shows that sound absorption coefficient obtained through experimental test and simulation were very good and comparable with the commercial noise absorption material such as synthetic fibre and rock wool. Transmission loss index for the panel using coir fibre gives a better results compared to panel using oil palm fibre. Key words: Acoustic materials; coir fibre; sound absorption coefficient; tranmission loss index; reverberation room

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).

scholarly journals Diffuse Sound Absorptive Properties of Parallel-Arranged Perforated Plates with Extended Tubes and Porous Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1091 ◽  
Author(s):  
Dengke Li ◽  
Daoqing Chang ◽  
Bilong Liu
Keyword(s):  
Boundary Condition ◽  
Porous Material ◽  
Porous Materials ◽  
Sound Absorption ◽  
Azimuthal Angle ◽  
Octave Band ◽  
Frequency Range ◽  
Absorption Coefficients ◽  
Perforated Plates ◽  
Absorption Performance

The diffuse sound absorption was investigated theoretically and experimentally for a periodically arranged sound absorber composed of perforated plates with extended tubes (PPETs) and porous materials. The calculation formulae related to the boundary condition are derived for the periodic absorbers, and then the equations are solved numerically. The influences of the incidence and azimuthal angle, and the period of absorber arrangement are investigated on the sound absorption. The sound-absorption coefficients are tested in a standard reverberation room for a periodic absorber composed of units of three parallel-arranged PPETs and porous material. The measured 1/3-octave band sound-absorption coefficients agree well with the theoretical prediction. Both theoretical and measured results suggest that the periodic PPET absorbers have good sound-absorption performance in the low- to mid-frequency range in diffuse field.

Method of Testing of Sound Absorption Properties of Materials Intended for Ultrasonic Noise Protection

2013 ◽  
Vol 38 (2) ◽  
pp. 191-195 ◽  
Author(s):  
Dariusz Pleban
Keyword(s):  
Sound Absorption ◽  
Free Field ◽  
Tone Burst ◽  
Mineral Wool ◽  
Frequency Range ◽  
Absorption Properties ◽  
Open Cell Foam ◽  
Properties Of Materials ◽  
Cell Foam

Abstract Efficient ultrasonic noise reduction by using enclosures requires the knowledge of absorbing properties of materials in the frequency range above 4 kHz. However, standardized methods enable determination of absorption coefficients of materials in the frequency range up to 4 kHz. For this reason, it is proposed to carry out measurements of the sound absorption properties of materials in the free field by means of a tone-burst technique in the frequency range from 4 kHz to 40 kHz at angles of incidence varying from 0° to 60°. The absorption coefficient of a material is calculated from the reflection coefficient obtained by reflecting a tone-burst from both a perfectly reflecting panel and a combination of this panel and the sample of the tested material. The tests results show that mineral wool and polyurethane open-cell foam possess very good absorbing properties in this frequency range.

scholarly journals A Novel Frequency Reconfigurable Microstrip Patch Antenna using Pin Diode

2020 ◽  
Vol 9 (5) ◽  
pp. 2013-2017
Keyword(s):  
Patch Antenna ◽  
Return Loss ◽  
Microstrip Patch Antenna ◽  
Pin Diode ◽  
Optimum Level ◽  
Frequency Range ◽  
Microstrip Patch ◽  
Single Antenna ◽  
Specific Frequency ◽  
Switching State

In recent study, in the growth of wireless technology single antenna that works with a specific frequency is becoming outdated. The antenna which is capable to work dynamically is encouraged. To make an antenna to work dynamically, modification in any of the antenna characteristics can be applied. In this proposed work, the antenna which can reconfigure its frequency is designed and analyzed. Microstrip patch antenna is most popular printed type antenna which is suitable for diverse applications. The antenna design consists of three PIN diodes which are placed in different positions on the patch. Depending upon the switching state of PIN diode the antenna can operate in different frequency ranges. The frequency range obtained ranges from 1.38 GHz to 3.24 GHz. Return loss value, VSWR obtained is of optimum level. The various gain of antenna is obtained in simulation. The analysis of the antenna is done in ANSYS HFSS software.

scholarly journals Non-Wovens as Sound Reducers

2018 ◽  
Vol 55 (2) ◽  
pp. 64-76
Author(s):  
D. Belakova ◽  
A. Seile ◽  
S. Kukle ◽  
T. Plamus
Keyword(s):  
Absorption Coefficient ◽  
Surface Density ◽  
Sound Absorption ◽  
Transmission Loss ◽  
Sound Transmission ◽  
Sound Insulation ◽  
Material Structure ◽  
Sound Transmission Loss ◽  
Sound Waves ◽  
Frequency Range

Abstract Within the present study, the effect of hemp (40 wt%) and polyactide (60 wt%), non-woven surface density, thickness and number of fibre web layers on the sound absorption coefficient and the sound transmission loss in the frequency range from 50 to 5000 Hz is analysed. The sound insulation properties of the experimental samples have been determined, compared to the ones in practical use, and the possible use of material has been defined. Non-woven materials are ideally suited for use in acoustic insulation products because the arrangement of fibres produces a porous material structure, which leads to a greater interaction between sound waves and fibre structure. Of all the tested samples (A, B and D), the non-woven variant B exceeded the surface density of sample A by 1.22 times and 1.15 times that of sample D. By placing non-wovens one above the other in 2 layers, it is possible to increase the absorption coefficient of the material, which depending on the frequency corresponds to C, D, and E sound absorption classes. Sample A demonstrates the best sound absorption of all the three samples in the frequency range from 250 to 2000 Hz. In the test frequency range from 50 to 5000 Hz, the sound transmission loss varies from 0.76 (Sample D at 63 Hz) to 3.90 (Sample B at 5000 Hz).

Utilization of Styrofoam ss Soundproofing Material with Auditory Frequency Range

2018 ◽  
Vol 13 (2) ◽  
Author(s):  
Sjahrul Meizar Nasri ◽  
Iting Shofwati
Keyword(s):  
Hearing Loss ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Noise Exposure ◽  
Preventive Action ◽  
Frequency Range ◽  
Acoustical Property ◽  
Noise Barrier ◽  
Polystyrene Waste ◽  
Action Methods

One of preventive action methods of hearing loss that number tend to increase is by using brick that made from Styrofoam which is expected to have the ability as a soundproof that can be used to control the noise. The aim of this research is to assess the use of sound absorption material in which utilizing Styrofoam to reduce the noise exposure. In this study, cement and find aggregate that contain the Styrofoam and sand are mixed with the composition 1:4 and 1:6 and also by adding the polystyrene waste as much as 0%, 20%, 40%, 60%, and 80%.  To determine the acoustical property of the mixture, the sound absorbing coefficient (α) was determined by using Four Microphones Impedance Tube (ISO 140-3). The results showed that the highest absorption coefficient value was at frequency 800 Hz by adding 80% Styrofoam for the composition of 1:4 at 0.4100 dB and at the frequency 800 Hz by adding 40% Styrofoam for the composition 1:6 at 0.5870 dB. Based on the results of this research, further study to potentially use Styrofoam as noise barrier is suggested.

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