scholarly journals Rating of Sound Absorption for EFBMF Acoustic Panels according to ISO 11654:1997

2018 ◽  
Vol 150 ◽  
pp. 03002 ◽  
Author(s):  
Emedya Murniwaty Samsudin ◽  
Lokman Hakim Ismail ◽  
Aeslina Abd Kadir ◽  
Ida Norfaslia Nasidi ◽  
Noor Sahidah Samsudin
Keyword(s):  
Sound Absorption ◽  
Empty Fruit Bunch ◽  
Initial Thickness ◽  
Reverberation Chamber ◽  
Sound Absorber ◽  
Class A ◽  
Class B ◽  
Absorption Performance

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.

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

2017 ◽  
Vol 36 (4) ◽  
pp. 376-398 ◽  
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.

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

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.

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.

On the sound absorption performance of a felt sound absorber

2016 ◽  
Vol 114 ◽  
pp. 275-280 ◽  
Author(s):  
Cem Meriç ◽  
Haluk Erol ◽  
Aytekin Özkan
Keyword(s):  
Sound Absorption ◽  
Sound Absorber ◽  
Absorption Performance

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.

scholarly journals The Effect of Different Fibre Length and Different Urea Formaldehyde (UF) content on Sound Absorption Performance of Empty Fruit Bunch (EFB)

2018 ◽  
Vol 150 ◽  
pp. 03003
Author(s):  
Ida Norfaslia Nasidi ◽  
Lokman Hakim Ismail ◽  
Emedya Murniwaty Samsudin ◽  
Muhamad Firdaus Abdul Khodir ◽  
Muhammad Aizat Kamarozaman
Keyword(s):  
Sound Absorption ◽  
Noise Control ◽  
Urea Formaldehyde ◽  
Fibre Length ◽  
Binder Content ◽  
Empty Fruit Bunch ◽  
Optimum Amount ◽  
Sound Absorber ◽  
Fibre Size ◽  
Alternative Material

Noise control is part of the major requirements to improve the living environment. One of the best methods to reduce noise is by employing sound absorber material into a space. Since traditional sound absorber in the market was believed could cause health problems to human, the need for alternative material is desired. This research intended to utilize waste materials from palm oil empty fruit bunch (EFB) in the production of natural sound absorber for noise control in building. Two parameters were investigated; the fibre length and binder content to determine their effect on sound absorption. Samples were tested using impedance tube using low and high frequencies according to ISO 10534-2:2001. Consequently, both parameters show that different fibre length and binder content affected the ability of the fibre to absorb sound. Results show that the optimum fibre size is in between 2mm to 5mm length while the optimum amount of binder is between 0% to 5% and 15% from fibre weight. This research has found that the highest Noise Reduction Coefficient (NRC) using 2mm to 5mm fibre size achieved 0.70 coefficients while the use of optimum amount of binder (particularly Urea Formaldehyde) could obtain 0.75 NRC. The newly develop panels are considered as a good sound absorbent and suitable to use as an alternative material replacing the synthetic absorber.

scholarly journals Effect of Diffusion Conditions on Absorption Performance of Materials Evaluated in Reverberation Chamber

2019 ◽  
Vol 11 (23) ◽  
pp. 6651
Author(s):  
Kyung Ho Kim ◽  
Jin Yong Jeon
Keyword(s):  
Absorption Coefficient ◽  
Edge Effect ◽  
Sound Absorption ◽  
Specimen Surface ◽  
Sound Absorption Coefficient ◽  
Accurate Estimation ◽  
Reverberation Chamber ◽  
Evaluation Indicator ◽  
Relative Standard ◽  
Absorption Performance

Obtaining the reverberation time of a multipurpose building is most effective when accurate data is used to simulate the building. Therefore, this study proposes a method of measuring the sound absorption coefficient that is close to the sound absorption performance of the conditions in which building materials are actually used. In addition, a sufficient diffusivity evaluation method for sound absorption coefficient measurement in a reverberation chamber is proposed, to address the sound absorption performance difference caused by internal diffusion of the reverberation chamber. When the sound absorption performance was evaluated after installing the specimen under the condition of minimized edge effect, the result obtained should closely match the sound absorption performance of the specimen surface. The sound absorption performance of the specimen ( α β E ≈ 0 ) with minimized edge effect and the sound absorption performance on the specimen surface ( α ∞ ) were proposed as an evaluation indicator of agreement between the values. Experimental results show that diffusion inside the reverberation chamber is enhanced when α ∞ − α β E ≈ 0 < 0.02, for which sufficient diffusion can be assumed inside the reverberation chamber. In addition, to verify the validity of the proposed evaluation indicator, we investigated the relationship with the objective diffusion evaluation indicator for diffuse field configuration in the reverberation chamber, such as relative standard deviation of decay rate ( S r e l ) and Np values. The results of this study are expected to contribute to a more accurate estimation of the sufficient diffusion condition in the reverberation chamber, in evaluating the sound absorption performance of the material, and that inside the reverberation chamber.

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

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.

مهارة الكلام منظور من عملية التعلم والتعليم في جامعة باتوسنجكر الاسلامية الحكومية سومطرى الغربية

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Suharmon Suharmon
Keyword(s):  
Teaching Strategies ◽  
Language Education ◽  
Arabic Language ◽  
Descriptive Statistics ◽  
Quantitative Approach ◽  
Motivation To Learn ◽  
Education Department ◽  
Class A ◽  
Class B ◽  
Speaking Skill

This research aims to obtain infomation about Arabic learning especially speaking skill in Arabic Language Education Department at IAIN Batusangkar. The research uses a quantitative approach. The instruments to collect the data are test and questionnaire. The data were analyzed using descriptive statistics. The results of the research state that the students’ speaking ability at class “ A “ are 28% low, 36% moderate, and 36% high. While, at class “B”, students’ speaking abilities are 36.4% low, 40,9% moderate, and 22.7% high. The cause of students’ low ability is the unappropriateness of teachers’ strategy in teaching speaking. There are about 96% students at class “A” agreed and 86.4% students at class “B” had similar answer. Another cause is students’ low motivation in learning. Class “A” students agreed for about 76% of them and 77% of class “B” students answered the same. From the finding, it can be concluded that the inability of students to speak Arabic can be overcomed by improving teaching strategies and encouraging maximum motivation  to learn Arabic.

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