Analysis of Sound Absorption of Date Palm Fibers Based on Flow Resistivity

2013 ◽  
Vol 471 ◽  
pp. 285-290 ◽  
Author(s):  
Elwaleed Awad Khidir ◽  
Mojahed Osman Mohammed Ali ◽  
Mohammed Mustafa Ali ◽  
Mohd Faizal Bin Mat Tahir ◽  
Rozli Zulkifli
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Date Palm ◽  
Single Layer ◽  
Sound Absorption Coefficient ◽  
Low Frequencies ◽  
Palm Fiber ◽  
Date Palm Fibers ◽  
Flow Resistivity ◽  
Fiber Sample

This paper presents a study on the sound absorption properties of a single layer date palm fiber based on the flow resistivity. Experimental measurements were carried out to estimate the flow resistivity value using differential pressure tube. The average diameter of the fibers is 0.462 mm. A date palm fiber sample of 25mm thickness is used in this research. The flow resistivity of the date palm fiber sample was found to be 4.26 kPa.s/m2. The flow resistivity was used to calculate the sound absorption coefficient using Delany and Bazley model. The simulation showed that the values of absorption coefficient are small at low frequencies and rising with increasing frequency. To check the effect of flow resistivity on the sound absorption coefficient Delany and Bazley model was simulated for three different flow resistivity values. The simulation results showed that the sound absorption coefficient increases with the increase of the flow resistivity.

A Preliminary Study on the Sound Absorption of Date Palm Fibers

2014 ◽  
Vol 663 ◽  
pp. 406-410
Author(s):  
Elwaleed Awad Khidir ◽  
Nik Abdullah Nik Mohamed ◽  
Mohd Jailani Mohd Nor ◽  
Mohd Faizal Mat Tahir ◽  
Rozli Zulkifli
Keyword(s):  
Sound Absorption ◽  
Date Palm ◽  
Single Layer ◽  
Air Gap ◽  
Constant Thickness ◽  
Frequency Range ◽  
Low Frequencies ◽  
Palm Fiber ◽  
Date Palm Fibers ◽  
Absorption Performance

In this study sound absorption properties of a single layer date palm fiber has been investigated. Experimental measurements were carried out using impedance tube at the acoustic lab, Faculty of Engineering, Universiti Kebangsaan Malaysia. A constant thickness sample was considered in this study.The results show that the values of absorption coefficient are small at low frequencies, rising with increasing frequency but exhibiting a significant peak. The low density of the sample is reflected in the overall sound absorption performance of the date palm fiber. An improvement in the sound absorption in the lower frequency range was achieved by backing the sample with air gap of different thicknesses of 10 mm, 20 mm and 30 mm. The increase in the air gap thickness moved the peaks toward lower frequencies and improved the low frequencies absorption. However, that increase coincided with reduction of absorption in medium frequency range and reduction in the absorption peak. A linear relationship was found between sound absorption peaks and the air gap thickness. The performance of the date palm fiber can be improved by increasing the density of the sample, using different sample thicknesses and adding perforated plates to the date palm fiber panel.

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.

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.

A Preliminary Study on the Sound Absorption of Self-Facing Date Palm Fibers

2014 ◽  
Vol 565 ◽  
pp. 25-30 ◽  
Author(s):  
Elwaleed A. Khidir ◽  
N. Nikabdullah ◽  
M.J.M. Nor ◽  
M.F.Mat Tahir ◽  
M.Z. Nuawi
Keyword(s):  
Sound Absorption ◽  
Date Palm ◽  
Perforated Plate ◽  
Low Frequency ◽  
Single Layer ◽  
Absorption Properties ◽  
Date Palm Fibers ◽  
Layer Sample ◽  
Good Improvement ◽  
Preliminary Study

Sound absorption of self-facing natural date palm fibershas been investigated.A single layer sample of the fibers was tested for its sound absorption properties. The sample was then faced with the originally date palm fiber netted structure. Experimental measurements were conducted on the impedance tube at the acoustic lab, Faculty of Engineering, UniversitiKebangsaan Malaysia, to determine the sound absorption coefficient.The single layer was also tested using an aluminum perforated plate, as facing, for comparison purposes.The results show a good improvement in the sound absorption for the self-facing panel for the whole frequency range. However, when using the aluminum perforated panel an improvement in the sound absorption was observed only above 2500 Hz. The effect of introducing air gap thickness was studied. The results show improvement for the sound absorption the low frequency.

Sound Absorption Characteristics of Porous Steel Manufactured by Lost Carbonate Sintering

2009 ◽  
Vol 1188 ◽  
Author(s):  
Miao Lu ◽  
Carl Hopkins ◽  
Yuyuan Zhao ◽  
Gary Seiffert
Keyword(s):  
Absorption Coefficient ◽  
Pore Size ◽  
Sound Absorption ◽  
Single Layer ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Absorption Coefficients ◽  
Impedance Tube ◽  
Absorption Characteristics

AbstractThis paper investigates the sound absorption characteristics of porous steel samples manufactured by Lost Carbonate Sintering. Measurements of the normal incidence sound absorption coefficient were made using an impedance tube for single-layer porous steel discs and assemblies comprising four layers of porous steel discs. The sound absorption coefficient was found not to vary significantly with pore size in the range of 250-1500 μm. In general, the absorption coefficient increases with increasing frequency and increasing thickness, and peaks at specific frequencies depending on the porosity. An increase in porosity tends to increase the frequency at which the sound absorption coefficient reaches this peak. An advantage was found in using an assembly of samples with gradient porosities of 75%-70%-65%-60% as it gave higher and more uniform sound absorption coefficients than an assembly with porosities of 75%.

scholarly journals Experimental Sound Absorption of Several Loose Uncooked Granular Materials

2019 ◽  
Vol 9 (1) ◽  
pp. 4578-4583
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Grain Shape ◽  
Experimental Tests ◽  
Sound Absorption Coefficient ◽  
Acoustic Absorption ◽  
Low Frequencies ◽  
Acoustic Insulation ◽  
Acoustic Absorption Coefficient ◽  
First Time

Absorbent materials it's an acoustic solution that can be used to control the reverberation time (RT) in deferent spaces as: conference rooms, in halls, theaters, cinema.... and also, it can be used in walls or ceilings of buildings to improve the acoustic insulation Which can be used for internal separations between spaces. This study focuses on the experimental study of the acoustic absorption coefficient of several granular food materials as a function of frequency 50 to 1600 Hz. All acoustic absorption tests performed in this study are performed by an acoustic impedance tube or Kundt tube. And to the knowledge of the author it is the first time in the literature that someone studies the acoustic behavior of this kind of materials. Several parameters were studied such as the effect of thickness on the sound absorption coefficient of the materials tested, like the influence of the grain form on the acoustic absorption by the introduction of a new parameter L / D, and finally the influence of density and type of material on the sound absorption coefficient. The objective of this work is to study the influence of the grain shape on the sound absorption coefficient, and that's why we have chosen these fifteen materials each one with its own shape. The results of these experimental tests show that when the sample thickness rises, the acoustic absorption coefficient rises too with a shift from resonance frequency to low frequencies. When the L/D parameter rises, the absorption behavior increases too in all frequencies mentioned. Finally, as the density of the tested material rises, the percentage of sound absorption of the materials also rises

Evaluation and comparison the properties of acoustic boards made of date palm fiber

BioResources ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. 7702-7715
Author(s):  
Mehdi Alishiri ◽  
Amir Hooman Hemmasi ◽  
Habibollah Khademi Eslam ◽  
Sedigheh Basirjafari ◽  
Mohammad Talaeipour
Keyword(s):  
Absorption Coefficient ◽  
Sodium Silicate ◽  
Sound Absorption ◽  
Date Palm ◽  
Agricultural Waste ◽  
Natural Fibers ◽  
Control Sample ◽  
Sound Absorption Coefficient ◽  
Synthetic Fibers ◽  
Particle Length

Applying acoustic panels made of natural fibers, due to their high biodegradable characteristics, light weight, low density, cheap price and non-toxicity, are proper alternatives to acoustic absorbers made of synthetic fibers. Considering their stance and vast applicability in industry, the possibility of producing them of natural palm fibers with sodium silicate adhesive of 10 and 20% in two 16 and 32 mm thicknesses, 350 and 450 kg/m3 densities, 50 and 100 mm particles length (strands), as variable factors in 16 types of matched panels with 3 repetitions is proposed in this article. The palm-trunk discs constituted the control sample. The effect of variables on sound absorption coefficient was assessed. The effect of variable thickness and adhesive percentage on all frequencies was significant and the effect of density variable on all frequencies except 250 and 2000 Hz was also significant. The effect of particle length was significant except at the 500 Hz frequency. The effects of all variables on porosity were significant. The results of this study suggest that by applying date palm-trunk (an agricultural waste) combined with sodium silicate adhesive, industrial environment-friendly panels can be produced with proper sound absorption coefficient in the field of acoustics. This 32-mm-thick panel was composed of 80% date palm-trunk particles of 50 mm length, 450 kg/m3 density, and 20% sodium silicate adhesive.

Measurement of sound absorption coefficient in a reverberant room using probability density function of damping constant

2021 ◽  
Vol 263 (4) ◽  
pp. 2940-2948
Author(s):  
Kosuke Goto ◽  
Takehiko Nakagawa ◽  
Yoshinari Yamada
Keyword(s):  
Probability Density Function ◽  
Absorption Coefficient ◽  
Spatial Variability ◽  
Measurement Method ◽  
Sound Absorption ◽  
Measurement Accuracy ◽  
Sound Absorption Coefficient ◽  
Reverberation Time ◽  
Low Frequencies ◽  
Sinusoidal Input

The measurement method of the sound absorption coefficient in a reverberation room is standardized in ISO 354. However, the measurement accuracy often deteriorates at low frequencies. This paper proposes a method that improves the measurement accuracy of the sound absorption coefficient at low frequencies. It calculates the sound absorption coefficient using reverberation time (RT) that is derived from the distribution of a damping constant for a sinusoidal input. The measured values by the proposed method were compared with those by the ISO 354 method. As a result, the proposed method reduces the spatial variability of RT and gives a better agreement with the statistical absorption coefficient that is calculated by a transfer matrix model at low frequencies.

scholarly journals Sound absorption characteristics of three species (binuang, balsa and paulownia) of low density hardwood

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Eun-Suk Jang ◽  
Chun-Won Kang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Gas Permeability ◽  
Sound Absorption Coefficient ◽  
Low Density ◽  
High Porosity ◽  
Sound Waves ◽  
Low Frequencies ◽  
Absorption Performance ◽  
Closed Pore

Abstract In this study, the sound absorption coefficient of three low density hardwoods – binuang, balsa and paulownia – were investigated. Their gas permeability and pore size were measured, and their pore shapes were classified into through pore, blind pored, and closed pore, as specified by the International Union of Pure and Applied Chemistry (IUPAC). Among the three species, obvious that paulownia had lowest sound absorption when the two of others showed higher sound absorption. Although paulownia is a high porosity wood, most of its vessels are blocked by tyloses; it is therefore difficult for sound waves to enter its pores, which results in poor sound absorption performance. This study showed that the higher the through pore porosity, the higher was the gas permeability, which led to improvement of the sound absorption performance. It was also found that the sound absorption coefficient of the three species woods increased at low frequencies as the size of an air cavity between the specimens and tube’s wall increased.

An Experimental and Simulation Studies on Sound Absorption Coefficients of Banana Fibers and their Reinforced Composites

2016 ◽  
Vol 12 ◽  
pp. 9-20 ◽  
Author(s):  
Muhammad Khusairy bin Bakri ◽  
Elammaran Jayamani ◽  
Soon Kok Heng ◽  
Sinin Hamdan ◽  
Akshay Kakar
Keyword(s):  
Absorption Coefficient ◽  
Empirical Model ◽  
Sound Absorption ◽  
Epoxy Composites ◽  
Sound Absorption Coefficient ◽  
Simulation Studies ◽  
Reinforced Composites ◽  
Banana Fiber ◽  
Banana Fibers ◽  
Flow Resistivity

This research focuses on the simulation of sound absorption coefficient of banana fiber and experimentation of sound absorption coefficient of banana fiber epoxy composites. For simulation, ‘Mechel’ empirical model was used to manipulate the flow resistivity and ‘Delany and Bazley’ empirical model was used to develop the prediction of sound absorption coefficient at frequency ranges from 500 Hz to 6000 Hz. For experimentation, two-microphone transfer function impedance tube model was used to analyze the sound absorption coefficient at frequency ranges from 500 Hz to 6000 Hz. Based on simulation, it is predicted and analyzed that the sound absorption coefficient of banana fiber found to be as high as 0.97 for the effects on the material thickness of banana fiber and 0.64 for the effects on the fiber diameter size and flow resistivity of banana fiber in the frequency ranges from 500 Hz to 6000 Hz. According to experimental results, it is observed and analyzed that the sound absorption coefficient of banana epoxy composites found to be as high as 0.11 for untreated banana epoxy composites and 0.12 for treated banana epoxy composites in the frequency ranges from 500 Hz to 6000 Hz.

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