Preliminary Study on Bamboo as Sound Absorber

2014 ◽  
Vol 554 ◽  
pp. 76-80 ◽  
Author(s):  
Fazlin A. Khair ◽  
Azma Putra ◽  
Mohd Jailani Mohd Nor ◽  
Nurul Atiqah ◽  
M.Z. Selamat
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Hollow Structure ◽  
Chemical Substance ◽  
The Body ◽  
Natural Material ◽  
Sound Absorber ◽  
Tube Test ◽  
Average Absorption Coefficient ◽  
Preliminary Study

Synthetic acoustic materials are known for their poisonous chemical substance to the environment and also the particles which are harmful to human health. Research is now directed towards finding an alternative acoustic absorber made from natural materials. This paper presents the utilization of bamboo, a natural material having hollow structure to act as sound absorber. In an impedance tube test, the hollow path is arranged to face the sound incidence. The result reveals that bamboo having length of 2 cm has average absorption coefficient of 0.95 at frequency above 3 kHz. Performance at lower frequencies can be controlled by adding the air gap behind the system. Introduction of microholes along the body shows no significant effect to increase the sound absorption.

Realizing high-efficiency low frequency sound absorption of underwater meta-structures by acoustic siphon effect

2021 ◽  
pp. 2150319
Author(s):  
Li Bo Wang ◽  
Cheng Zhi Ma ◽  
Jiu Hui Wu ◽  
Chong Rui Liu
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
High Efficiency ◽  
Physical Mechanism ◽  
Low Frequency ◽  
Area Ratio ◽  
Underwater Acoustic ◽  
Element Simulation ◽  
Average Absorption Coefficient ◽  
New Perspective

The underwater acoustic siphon effect is proposed in this work, which aims to reveal the basic physical mechanism of high-efficiency sound absorption in meta-structures composed of multiple detuned units. Furthermore, the influence of the area ratio on the underwater acoustic siphon effect is then investigated by finite element simulation (FES) and theoretical calculation. On this basis, a meta-structure with the maximum absorption coefficient of almost 100% and average absorption coefficient of 80% at 600–1400 Hz is achieved. The underwater acoustic siphon effect could provide a better understanding of high-efficiency sound absorption and offer a new perspective in controlling underwater noises.

Utilization of Treated Red Meranti Wood Dust as Polymer Foam Composite for Acoustic Study

2013 ◽  
Vol 594-595 ◽  
pp. 760-764 ◽  
Author(s):  
Shafizah Sa'adon ◽  
Anika Zafiah M. Rus
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Wood Dust ◽  
Polymer Foam ◽  
Tube Test ◽  
Acoustic Study ◽  
Foam Composite ◽  
Absorbing Materials ◽  
Scanning Electron

A Red Meranti Wood Dust (RMD) act as a filler for polymer foam composite has been investigated and proved to have ability to absorb sound. In this study, treatment of wood dust with and without acid hydrolysis named as WDB and WDA respectively was use as filler. This study was developed to compare the ability of sound absorption based on treated filler and particle size of wood dust. By choosing the size of 355 μm, three different percentage has been selected which is 10%, 15% and 20% for both conditions. These samples has been tested by using Impedance Tube test according to ASTM E-1050 for sound absorption coefficient, α measurement and Scanning Electron Microscopy (SEM) for determine the porosity for each samples. 10% loaded of WDB as filler gives highest sound absorption coefficient of 0.999 at 4015.63 Hz. Meanwhile for 20% loaded of WDA gives 0.997 at 3228.13 Hz. When comparing the sound absorption coefficient for both sounds absorbing materials, WDB-polymer foam composite RMD showed higher value of sound absorption coefficient, α at higher frequency as compared to WDA-polymer foam composite.

Utilizing Hollow-Structured Bamboo as Natural Sound Absorber

2015 ◽  
Vol 40 (4) ◽  
pp. 601-608 ◽  
Author(s):  
Azma Putra ◽  
Fazlin Abd Khair ◽  
Mohd Jailani Mohd Nor
Keyword(s):  
Absorption Coefficient ◽  
Hollow Structure ◽  
Front Surface ◽  
Normal Incidence ◽  
Frequency Range ◽  
Peak Absorption ◽  
Natural Sound ◽  
Average Absorption Coefficient ◽  
Lower Frequency Range ◽  
Bamboo Structure

AbstractStudies to find alternative low environmental-impact materials for acoustic absorbers are still progressing, particularly those originated from natural materials. However, most of the established works are mainly focused on the fibrous-type absorbers. Discussion on the non-fibrous-type absorbers is still lacking and this therefore becomes the objective of this paper. Use of bamboo by utilizing its hollow structure to absorb sound energy is discussed here. The normal incidence absorption coefficient was measured based on the length and diameter of the bamboo, as well as different arrangement of the bamboo structure subjected to the incidence sound, namely, axial, transverse, and crossed-transverse arrangements. The trend of absorption coefficient appears in peaks and dips at equally spacing frequencies. For all arrangements the peak of absorption can reach above 0.8. Introducing an air gap behind the bamboo shifts the peak absorption to lower frequency. Covering the front surface of the absorber improves the sound absorption coefficient for axial arrangement by widening the frequency range of absorption also towards lower frequency range. The transverse arrangement is found to have average absorption coefficient peaks of 0.7 above 1.5 kHz. By arranging the bamboo structure with crossed-transverse arrangement, the suppressed absorption peaks in normal transverse arrangement can be recovered.

scholarly journals Effect of Porous Materials Combination in Layers on Sound Absorption Characteristics

2015 ◽  
Vol 773-774 ◽  
pp. 210-215
Author(s):  
Muhd Hafeez Zainulabidin ◽  
M.H.M. Yusuff ◽  
Al Emran Ismail ◽  
M.Z. Kasron ◽  
A.S.M. Kassim
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Low Frequency ◽  
Sound Absorption Coefficient ◽  
Frequency Range ◽  
Sound Absorber ◽  
Number Of Layers ◽  
Combination Number ◽  
Impedance Tubes ◽  
Absorption Characteristics

This paper describes the investigation and analysis on two materials in which one material is a relatively good sound absorber at low frequency range and another is a relatively good sound absorber at high frequency range, combined together in layers to form a better sound absorber for a wider range of frequencies. The layer combinations of the materials are varied and the values of Sound Absorption Coefficient, α are measured experimentally by using impedance tubes with two microphones transfer function method according to ISO 10534-2 standard. The results obtained are compared in terms of the order of material and the number of layer combinations of materials for each sample. The orders of combinations and number of layers of combinations have significant influence on the sound absorption characteristics. The order of materials has reversed effect on Sound Absorption Coefficient, α as the number of layer combination is increased. Increase in the combination number will make the specimen performed relatively better at a wider frequency range.

scholarly journals Acoustic Properties of Sound Absorber from Modified Polyester with Filler Sodium Bicarbonate

2018 ◽  
Vol 34 (4) ◽  
pp. 2187-2191
Author(s):  
Nasmi Herlina Sari ◽  
Jauhar Fajrin
Keyword(s):  
Absorption Coefficient ◽  
Sodium Bicarbonate ◽  
Acoustic Impedance ◽  
Sound Absorption ◽  
Polyester Resin ◽  
Acoustic Properties ◽  
Acoustic Parameters ◽  
Absorbent Material ◽  
Sound Absorber ◽  
Absorption Performance

The combination of low price, ease of manufacturing and waterproofing characteristics has placed polyester resin as a potential sound absorbent material. Previous studies showed that adding filler material to the blending may increase the acoustics properties of a sound absorbent material. This study aims to investigate the potential of sodium bicarbonate (NaHCO3) to be employed as a filler to improve the acoustic properties of the sound absorber made of polyester resin. Two important acoustic parameters were carefully assessed; absorption coefficient and acoustic impedance. The results showed that the sound absorption performance increased significantly at low and medium frequencies in the presence of NaHCO3 filler in polyester resin. Meanwhile, the use of a back cavity on the absorbent material reduced the sound absorption performance of materials at low and medium frequencies. This suggests that sound absorber made of polyester with sodium bicarbonate filler may be used as an alternative for sound absorber materials.

Analysis of Absorption Coefficient for Eco-Friendly Acoustical Absorbers

2013 ◽  
Vol 831 ◽  
pp. 58-61
Author(s):  
Jun Oh Yeon ◽  
Kyoung Woo Kim
Keyword(s):  
Absorption Coefficient ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Glass Wool ◽  
Absorption Coefficients ◽  
Sound Absorber ◽  
Reduction Coefficient ◽  
Absorption Performance ◽  
Rock Wool

Primarily used for domestic buildings as a sound absorber are glass wool, rock wool, etc. These absorbers as well as waste absorber created by recycling wastes, PP+PET fiber absorber made from polypropylene and polyester, wood wool board bonded with finely sliced roots of trees and foamed aluminum absorber are recyclable eco-friendly absorbers that are constantly being developed. In this study, we compared the sound absorption performance of currently used absorbers and eco-friendly building absorbers. As a result, the NRC (Noise Reduction Coefficient) was found to be 0.85 for glass wool, 0.95 for rock wool, and 0.70 for polyester, 0.65 for waste absorber, 0.75 for PET+ PP fiber absorber, 0.40 for wood wool board, and 0.75 for foamed aluminum absorber. Based on the results of these absorption coefficients, we expect the usability of the absorbers continues to increase as future eco-friendly building absorbers.

Effect of Percentage Ratio of Hydroxylated Biomonomer with Synthetic Epoxy of Polymer Foam for Sound Absorption Study

2013 ◽  
Vol 465-466 ◽  
pp. 1034-1038 ◽  
Author(s):  
Noor Quratul Aine Adnan ◽  
Anika Zafiah M. Rus
Keyword(s):  
Absorption Coefficient ◽  
Vegetable Oil ◽  
Sound Absorption ◽  
Acoustic Property ◽  
The Other ◽  
Absorption Study ◽  
Polymer Foam ◽  
Impedance Tube ◽  
Tube Test ◽  
Percentage Ratio

Biopolymer foam was prepared based on vegetable oil and Polyol Flexible (Epoxy) with commercial Polymethane Polyphenyl Isocyanate (Modified Polymeric-MDI) with the different proportion ratio. This research is to study the acoustic property between different proportion ratio of biomonomer and epoxy. The acoustic property of biopolymer foam was examined by using an impedance tube test according to ASTM E-1050 of sound absorption coefficient (α). Based on the result obtained, mostly the values of α were consistent at the samples F. It was observed that, sample F gave the highest value of α that is 0.997 at of 3500Hz. Sample F from ratio 100:0 from epoxy to biomonomer and gave the best sound absorption than the other foam. So, different ratio give different α at different frequency (Hz).

Preparation and Performance of Porous Silica of Sound-Absorbing Coating

2012 ◽  
Vol 568 ◽  
pp. 307-310 ◽  
Author(s):  
Jin Chen ◽  
Xiao Gang Wang ◽  
Min Zhang ◽  
Ai Xia Guo ◽  
Lei Tang
Keyword(s):  
Wear Resistance ◽  
Acrylic Acid ◽  
Absorption Coefficient ◽  
Acid Ester ◽  
Sound Absorption ◽  
Porous Silica ◽  
Curing Agent ◽  
Absorption Properties ◽  
Average Absorption Coefficient ◽  
And Performance

Using the poly-acrylic acid ester modified porous silica as fillers, the E-44 epoxy resin as matrix, ethylene diamine as curing agent prepared the sound absorption coating, and the sound absorption properties of and wear resistance were tested. The results showed that: the coating wear resistance increased with the addition of filler increasing，and then decreased. The wear mass of 60%filler coating is the lowest. The absorption coefficient increases with the filler increasing, the average absorption coefficient can reach 0.22 of 1000Hz frequency sound.

scholarly journals Acoustic Absorption Characteristics of Porous Asphalt Containing Coconut Shells

2019 ◽  
Vol 8 (3S3) ◽  
pp. 327-331
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Maximum Density ◽  
Acoustic Absorption ◽  
Impedance Tube ◽  
Porous Asphalt ◽  
Tube Test ◽  
Resistance To Oxidation ◽  
Coconut Shells ◽  
Absorption Characteristics

In this study, coconut shells were used as aggregate replacement in porous asphalt to observe its effect on sound absorption through Impedance Tube test. For coconut shells aggregate porous asphalt to be used in realistic situations it is essential to ensure its mix integrity, resistance to oxidation and raveling as well as its durability; therefore, the Cantabro Test, Binder drain-down test and Theoretical Maximum Density were also conducted in this study. The result showed that porous asphalt containing coconut shells exhibited significance improvement of sound absorption. The sound absorption coefficient of porous asphalt incorporating 10%, 30% and 50% of coconut shells approximately at the peak of the curve which is at the frequency of 850hz are 0.93, 0.96 and 0.93 while for conventional porous asphalt is 0.89. This study also found that porous asphalt containing 10 - 50% of coconut shells contributed a significance improvement in sound absorption compare than conventional porous asphalt at the frequency of 200 – 1600 Hz. However, only porous asphalt containing 10% of coconut shells satisfied all the parameters tested similar to the conventional porous asphalt.

scholarly journals Method to Recycle Paper Sludge Waste: Production of Panels for Sound Absorption Applications

2020 ◽  
Vol 24 (3) ◽  
pp. 364-372
Author(s):  
Tomas Astrauskas ◽  
Raimondas Grubliauskas
Keyword(s):  
Waste Management ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Power Plants ◽  
Waste Utilization ◽  
Sound Absorption Coefficient ◽  
Natural Material ◽  
Paper Sludge ◽  
The European Union ◽  
Sludge Waste

AbstractPaper sludge is the water treatment waste, which produced during paper production. Paper sludge (PS) waste utilization is the common problem in the EU and internationally. According to the waste management directive No. 2008/98/EC, paper sludge waste should not be utilized in landfills. In the European Union, alone 93 million tons of PS generated yearly. Nowadays most of the paper sludge waste used as fuel for incineration power plants (up to 55 %). According to waste management legislation such waste management should be avoided as well. Very small portion (10 %) of PS is used in construction sector. In construction, paper sludge used as additive in concrete composite materials. Such legislation of waste management generates the motivation of this study. In this study authors propose to produce composite panels in which PS is the main material of composite. As the binding material, clay proposed due to its good binding properties and therefore its natural material. Such produced panels proposed to use it for sound absorption applications. To determine composites sound absorption coefficient standard ISO 10534-2 method was used. The sound absorption coefficient in different octave bands reached up to 0.59.

Sign in / Sign up

Export Citation Format

Share Document