On the sound absorption performance of a felt sound absorber

Empty fruit bunch fibre (EFB) and mesocarp fibre (MF) have been used in the fabrication of a new acoustic panel as a sound absorber for building. Measurements were carried out following ISO 354 in the mini reverberation chamber and the sound absorption performance of EFBMF acoustic panels were rated based on ISO 11654. Measurements of the new EFBMF acoustic panel involves five panel designs of 100 EFB dust panels, 80:20 dust panels, 100MF coir panels, 90:10 coir panels and 50:50 coir panels with 5 cm of initial thickness. Results showed that 100MF coir panel achieved αw of 0.90 coefficient and was rated as Class A absorber followed by 90:10 coir panels with αw of 0.85 coefficient and 100 EFB dust, 80:20 dust and 50:50 coir panels having αw of 0.80 coefficients and been rated as Class B absorber. This research has successfully defined that EFB and MF are viable to be used as raw fibre for acoustic absorber for building.

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Improvement of the sound absorption performance of jute felt-based sound absorbers using micro-perforated panels

Journal of Low Frequency Noise Vibration and Active Control ◽

10.1177/1461348417744307 ◽

2017 ◽

Vol 36 (4) ◽

pp. 376-398 ◽

Cited By ~ 6

Author(s):

Pritesh V Bansod ◽

T Sai Teja ◽

Amiya R Mohanty

Keyword(s):

Transfer Matrix Method ◽

Sound Absorption ◽

Low Cost ◽

Control Engineering ◽

Natural Materials ◽

Sound Absorber ◽

Absorbing Materials ◽

Different Types ◽

Absorbing Material ◽

Absorption Performance

In industrial and architectural applications, noise can be controlled using sound-absorbing materials. Natural materials are now gaining importance in the noise control engineering as they have advantages like low cost, eco-friendly, easy to produce, etc. Jute is one of such natural materials, which can be used as a sound-absorbing material. Micro-perforated panels along with three different types of jute felts are used in a multilayer sound absorber configuration to improve its sound absorption. The sound absorption performance of these multilayer sound absorbers is evaluated by using the transfer matrix method and experimental method. Dependence of sound absorption performance on the placement of micro-perforated panels in a multilayer sound absorber is also studied. It is observed that the sound absorption performance depends on the position of micro-perforated panels in a multilayer sound absorber.

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A Compact Hybrid Sound Absorber Using Flexible Micro-Perforated Panel and Piezoelectric Actuator

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.325-326.8 ◽

2013 ◽

Vol 325-326 ◽

pp. 8-11

Author(s):

Wei Guang Zheng ◽

Ying Feng Lei ◽

Qi Bai Huang ◽

Chuan Bing Li

Keyword(s):

Hybrid System ◽

Piezoelectric Actuator ◽

Sound Absorption ◽

Low Frequency ◽

Combined Approach ◽

High Frequencies ◽

Sound Absorber ◽

Vibration Effect ◽

Piezoelectric Patch ◽

Absorption Performance

This paper presents the concept of a compact hybrid sound absorber, based on a combined approach for sound absorption. A flexible micro-perforated panel (MPP) is used as the passive sound absorber for mid and high frequencies and a piezoelectric patch as the active control actuator for low frequency. The volume of this new absorber is highly reduced compare to conventional hybrid systems which employ porous layer as passive part and loudspeaker as active part. The vibration effect of the MPP in the hybrid system is also considered. Theoretical and experimental results show that the flexible MPP has the potential to dissipate more energy and can be utilized to improve absorption performance of the hybrid system by appropriately selecting its parameters.

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

Oriental Journal Of Chemistry ◽

10.13005/ojc/3404061 ◽

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.

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Analysis of Absorption Coefficient for Eco-Friendly Acoustical Absorbers

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.831.58 ◽

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.

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Investigation of Acoustic Properties on Wideband Sound-Absorber Composed of Hollow Perforated Spherical Structure with Extended Tubes and Porous Materials

Applied Sciences ◽

10.3390/app10248978 ◽

2020 ◽

Vol 10 (24) ◽

pp. 8978

Author(s):

Dengke Li ◽

Zhongcheng Jiang ◽

Lin Li ◽

Xiaobo Liu ◽

Xianfeng Wang ◽

...

Keyword(s):

Sound Absorption ◽

Three Dimensional ◽

Low Frequency ◽

Acoustic Properties ◽

Low Frequencies ◽

Frequency Sound ◽

Sound Absorber ◽

Spherical Structure ◽

Absorption Performance ◽

Melamine Foam

Traditional porous media such as melamine foam absorb sound due to their three-dimensional porous struts. However, the acoustic properties at low frequencies are greatly related to its thickness. In this paper, a novel type of thin and lightweight sound absorber composed of melamine foam and hollow perforated spherical structure with extended tubes (HPSET) is introduced to enhance the sound absorption performance at low frequencies. A theoretical model for the normal absorption coefficient of the HPSET with melamine foam is established. Good agreements are observed between the simulated and the experimental results. Compared with the virgin melamine foam, the proposed absorber can greatly improve the low-frequency sound absorption and retain the mid- to high-frequency sound absorption, while the thickness of the proposed absorber is less than 1/28 of the wavelength.

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Sound absorption performance of flexible polyurethane/silicon dioxide perforated coating composites

Textile Research Journal ◽

10.1177/00405175211015516 ◽

2021 ◽

pp. 004051752110155

Author(s):

Min Peng ◽

Xiaoming Zhao ◽

Weibin Li

Keyword(s):

Silicon Dioxide ◽

Sound Absorption ◽

Woven Fabric ◽

Perforation Rate ◽

Cavity Depth ◽

Resonant Frequencies ◽

The Matrix ◽

Absorption Performance ◽

Traditional Sense ◽

Flexible Polyurethane

Perforated materials in the traditional sense are rigid, usually dense, costly and inflexible. For this study, polyester/cotton blended woven fabric as the base fabric, nano-SiO2 (silicon dioxide) as the functional particles and PU (polyurethane) as the matrix were selected. Accordingly, flexible PU/SiO2 perforated coating composites with different process parameters were developed. The inﬂuence of the nano-SiO2 content, perforation diameter, perforation rate, number of fiber felt layers and cavity depth on the sound absorption coefficient were investigated. The resonant frequencies of materials with different cavity depths were evaluated by both theoretical calculation and experimental method. It was found that the flexible perforated composite has good sound absorption and mechanical properties, and has great potential for applications requiring soft and lightweight sound absorption materials.

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

Materials ◽

10.3390/ma13051091 ◽

2020 ◽

Vol 13 (5) ◽

pp. 1091 ◽

Cited By ~ 1

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.

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Application of transparent microperforated panel to acrylic partitions for desktop use: A case study by prototyping

10.14324/111.444/000076.v2 ◽

2021 ◽

Author(s):

Kimihiro Sakagami ◽

Midori Kusaka ◽

Takeshi Okuzono ◽

Shigeyuki Kido ◽

Daichi Yamaguchi

Keyword(s):

Adverse Effect ◽

Sound Absorption ◽

Acoustic Environment ◽

Actual Use ◽

Acrylic Sheet ◽

Absorption Performance ◽

The Subject ◽

Droplet Penetration ◽

Absorption Characteristics

There are various measures currently in place to prevent the spread of COVID-19; however, in some cases, these can have an adverse effect on the acoustic environment in buildings. For example, transparent acrylic partitions are often used in eating establishments, meeting rooms, offices, etc., to prevent droplet infection. However, acrylic partitions are acoustically reflective; therefore, reflected sounds may cause acoustic problems such as difficulties in conversation or the leakage of conversation. In this study, we performed a prototyping of transparent acrylic partitions to which a microperforated panel (MPP) was applied for sound absorption while maintaining transparency. The proposed partition is a triple-leaf acrylic partition with a single acrylic sheet without holes between two MPP sheets, as including a hole-free panel is important to a possible droplet penetration. The sound absorption characteristics were investigated by measuring the sound absorption in a reverberation room. As the original prototype showed sound absorption characteristics with a gentle peak and low values due to the openings on the periphery, it was modified by closing the openings of the top and sides. The sound absorption performance was improved to some extent when the top and sides were closed, although there remains the possibility of further improvement. This time, only the sound absorption characteristics were examined in the prototype experiments. The effects during actual use will be the subject of future study.

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