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 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.

scholarly journals Elucidating the Sound Absorption Characteristics of Foxtail Millet (Setariaitalica) Husk

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5126
Author(s):  
Dhayalini Balasubramanian ◽  
Senthil Rajendran ◽  
Bhuvanesh Srinivasan ◽  
Nirmalakumari Angamuthu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Foxtail Millet ◽  
Air Gap ◽  
Composite Panel ◽  
Sound Absorption Coefficient ◽  
Mass Content ◽  
Frequency Range ◽  
Backing Material ◽  
Absorption Characteristics

The current study deals with the analysis of sound absorption characteristics of foxtail millet husk powder. Noise is one the most persistent pollutants which has to be dealt seriously. Foxtail millet is a small seeded cereal cultivated across the world and its husk is less explored for its utilization in polymer composites. The husk is the outer protective covering of the seed, rich in silica and lingo-cellulose content making it suitable for sound insulation. The acoustic characterization is done for treated foxtail millet husk powder and polypropylene composite panels. The physical parameters like fiber mass content, density, and thickness of the composite panel were varied and their influence over sound absorption was mapped. The influence of porosity, airflow resistance, and tortuosity was also studied. The experimental result shows that 30-mm thick foxtail millet husk powder composite panel with 40% fiber mass content, 320 kg/m3 density showed promising sound absorption for sound frequency range above 1000 Hz. We achieved noise reduction coefficient (NRC) value of 0.54. In view to improve the performance of the panel in low-frequency range, we studied the efficiency of incorporating air gap and rigid backing material to the designed panel. We used foxtail millet husk powder panel of density 850 kg/m3 as rigid backing material with varying air gap thickness. Thus the composite of 320 kg/m3 density, 30-mm thick when provided with 35-mm air gap and backing material improved the composite’s performance in sound frequency range 250 Hz to 1000 Hz. The overall sound absorption performance was improved and the NRC value and average sound absorption coefficient (SAC) were increased to 0.7 and 0.63 respectively comparable with the commercial acoustic panels made out of the synthetic fibers. We have calculated the sound absorption coefficient values using Delany and Bezlay model (D&B model) and Johnson–Champoux–Allard model (JCA model) and compared them with the measured sound absorption values.

Application of In Situ Method for Measuring Sound Absorption Coefficient of Direct Piercing Carved Wood Panel with Daun sireh Motif

2013 ◽  
Vol 471 ◽  
pp. 273-278
Author(s):  
Mohd Zamri Bin Jusoh ◽  
Mohamad Ngasri Dimon ◽  
Nazli Bin Che Din ◽  
Toru Otsuru ◽  
You Kok Yeow
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Wood Panel ◽  
Natural Sunlight ◽  
Absorption Performance ◽  
Air Circulation ◽  
Lower Frequencies

An application of In-Situ method of measuring sound absorption coefficient on the surface of direct piercing carved wood panel using the concept of ensemble averaged is discussed. The method offer an easier way to measure the absorption performance for each individual aperture of carved wood panel with floral pattern which was replicated from one of the oldest mosque, namely Masjid Abidin located in Terengganu, Malaysia. Two pieces of 20 mm thick of cengal wood (Neobalanocarpus heimii) with 30% and 40% perforation ratio were respectively measured in a reverberation room in order to determine the value of . At lower frequencies (0.1 kHz-1.5 kHz), the measured values of for both direct piercing carved wood panel with floral pattern (Daun Sireh motif) are shown that the sound absoption for both direct piercing carved wood panel are in perform level. From the measurements, clearly, the installation of the direct piercing carved wood panel with floral pattern (Daun Sireh motif) in the Masjid Abidin can provide better air circulation and additional natural sunlight, as well as better sound intelligibility inside the building.

scholarly journals Effect of Thickness and Perforation Size on the Acoustic Absorption Performance of a Micro-Perforated Panel

2021 ◽  
Vol 335 ◽  
pp. 03016
Author(s):  
Yi-San Wong ◽  
Vignesh Sekar ◽  
Se Yong Eh Noum ◽  
Sivakumar Sivanesan
Keyword(s):  
Absorption Coefficient ◽  
Urban Areas ◽  
Sound Absorption ◽  
Rapid Development ◽  
Noise Pollution ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Acoustic Absorption ◽  
Psychological Disturbance ◽  
Absorption Performance

In current times, noise pollution is especially apparent in urban areas due to rapid development in transportation, industrialization, and urbanization. The worsening noise pollution is detrimental to human health and behaviour as it can contribute to disorders and psychological disturbance. Thus, noise regulation is crucial and must be addressed with immediate effect. Micro-perforated panels (MPP) can be a potential solution to mitigate noise on a commercial scale. Researchers have addressed the mechanics behind the enhancement of acoustic absorption through micro-perforation and some suggestions have been made, such as the effect of structural variation on sound absorption performance. Hence, this research aims at optimizing the sound absorption performance of an MPP by determining the connection between thickness and perforation size with sound absorption coefficient. Three cases were considered: (i) varying perforation size, (ii) varying thickness, and (iii) varying perforation size and thickness simultaneously. Based on the Maa prediction model, the sound absorption performance for all three cases have been simulated through the MATLAB software. Results show that the increase in both thickness and perforation size together increases the peak value of sound absorption coefficient (SAC). It also shifts the peak towards the higher frequency region and narrows the bandwidth. The findings of this study indicate the potential of thick MPPs as commercial sound absorbers by adjusting the size of perforations. Thicker and sturdier MPPs with optimal acoustic resistance and reactance can act as reliable sound absorbers for sound insulation purposes.

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

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 Building Sound Absorption Performance Model of Porous Glass Based on GRNN

2019 ◽  
Vol 37 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Xubo Zhang ◽  
Ying Xu ◽  
Tingying Zhang ◽  
Guodong Li
Keyword(s):  
Absorption Coefficient ◽  
Porous Glass ◽  
Sound Absorption ◽  
Performance Model ◽  
Sound Absorption Coefficient ◽  
Average Error ◽  
Generalized Regression Neural Network ◽  
Prediction Curve ◽  
Absorption Performance ◽  
Two Parameters

The generalized regression neural network (GRNN) model of sound absorption coefficient of porous glass was built on data from 16 groups gained by experiments, where 12 groups were randomly selected as trained samples and the other 4 groups were as tested ones. This GRNN model which has two parameters, porosity and thickness as the inputs, was set the maximum iteration number 20, getting the optimal trained spread parameter σ=0.1. The results showed that the average error of this model was 0.003, and this model has high precision and the prediction curve of the sound absorption coefficient was very similar to the experiments. The advantages of this method are simple, needing less trained samples, rapid and accurate.

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.

Acoustic Absorption Performance Research of Coir Density Board

2012 ◽  
Vol 549 ◽  
pp. 589-592
Author(s):  
Jia Yao ◽  
Li Li Ma ◽  
Lu Wei ◽  
Li Wei Jiang ◽  
Ya Qin Li
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Optimization Design ◽  
Morphological Characteristics ◽  
Wave Impedance ◽  
Sound Absorption Coefficient ◽  
Coir Fiber ◽  
Tropical Fruit ◽  
Practical Applications ◽  
Absorption Performance

Coir fiber is one of the tropical fruit fibers, the effective use of coir is not comprehensive now and the phenomenon of resources waste still exists. Full study of the advantage characteristics of coir has important significance for the expansion of the application field of coir resources. This article determines the light porous characteristics of coir from the micro-morphological characteristics. Through the prediction model research of the sound absorption coefficient of the porous fiber materials, the optimization density and the optimization thickness ranges can be got for the coir density board, so as to guide the optimization design of the sound absorption performance of coir density board. The changing rule of the sound absorption coefficient of the coir density board has been got by adopting the wave impedance tube method and the sound absorption coefficients by adding 5cm air gap has also been researched. The results of the experiments confirm that coir density board can be used as a secondary noise absorption material; the practical applications of coir density board are as the lightweight wall, the car interior trim or seat filling materials and the shipping cabins materials, to reduce the corresponding environment noise.

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