scholarly journals Prediction of normal sound absorption coefficient for multi layer sound absorbing materials by using the boundary element method.

1990 ◽  
Vol 56 (532) ◽  
pp. 3248-3252 ◽  
Author(s):  
Hideo UTSUNO ◽  
Toshimitsu TANAKA ◽  
Yoshitaka MORISAWA ◽  
Toshio YOSHIMURA
Keyword(s):  
Boundary Element Method ◽  
Absorption Coefficient ◽  
Boundary Element ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Absorbing Materials ◽  
Element Method

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.

scholarly journals Predicted Absorption Performance of Cylindrical and Rectangular Permeable Membrane Space Sound Absorbers Using the Three-Dimensional Boundary Element Method

2019 ◽  
Vol 11 (9) ◽  
pp. 2714 ◽  
Author(s):  
Masahiro Toyoda ◽  
Kota Funahashi ◽  
Takeshi Okuzono ◽  
Kimihiro Sakagami
Keyword(s):  
Boundary Element Method ◽  
Boundary Element ◽  
Dimensional Analysis ◽  
Prediction Accuracy ◽  
Sound Absorption ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Permeable Membrane ◽  
Dimensional Boundary ◽  
Element Method

Three-dimensional, permeable membrane space sound absorbers have been proposed as practical and economical alternatives to three-dimensional, microperforated panel space sound absorbers. Previously, the sound absorption characteristics of a three-dimensional, permeable membrane space sound absorber were predicted using the two-dimensional boundary element method, but the prediction accuracy was impractical. Herein, a more accurate prediction method is proposed using the three-dimensional boundary element method. In the three-dimensional analysis, incident waves from the elevation angle direction and reflected waves from the floor are considered, using the mirror image. In addition, the dissipated energy ratio is calculated based on the sound absorption of a surface with a unit sound absorption power. To validate the three-dimensional numerical method, and to estimate the improvement in prediction accuracy, the results are compared with those of the measurements and two-dimensional analysis. For cylindrical and rectangular space sound absorbers, three-dimensional analysis provides a significantly improved prediction accuracy for any shape and membrane sample that is suitable for practical use.

COMPARISON OF NORMAL INCIDENT SOUND ABSORPTION COEFFICIENT OF DIRECT PIERCING CARVED WOOD PANEL FOR CIRCULAR, GEOMETRY AND FLORAL DESIGN

2016 ◽  
Vol 78 (6-10) ◽  
Author(s):  
Mohd Zamri Jusoh ◽  
Nazli Che Din ◽  
Mohamad Ngasri Dimon
Keyword(s):  
Boundary Element Method ◽  
Absorption Coefficient ◽  
Sound Absorption ◽  
Sound Intensity ◽  
Normal Incidence ◽  
Sound Absorption Coefficient ◽  
Wood Panel ◽  
High Frequencies ◽  
Wood Carving ◽  
Circular Design

Direct Piercing Carved Wood Panel (DPCWP) is among the famous Malay wood carving art in the Malay culture. It is the best example of Malay people’s creativity and masterpiece. In this paper, the comparison of normal incidence sound absorption coefficient,  (SAC) for three major types of design for the DPCWP is discussed. The simplest form of DPCWP, the circular type, then the geometry and floral types were investigated based on simulation and measurement works using sound intensity method to determine the normal incidence SAC, for 30% and 40% perforation ratios. The simulation work was carried out by using BEASY Acoustic software based on Boundary Element Method (BEM). From the results, there is an identical trend for DPCWP with geometry and floral design from 250 Hz to 4 kHz. At high frequencies (1 kHz to 4 kHz), both design show the tendency of decrement, suggesting that the complexity of the design does affect the average SAC value. However, for circular design, SAC is higher than other design at 1 kHz and shows a similar trend with other design at 2 kHz and 4 kHz for both simulation and measurement result.

Method of Determining the Sound Absorbing Coefficient of Materials within the Frequency Range of 5 000–50 000 Hz in a Test Chamber of a Volume of about 2 m3

2013 ◽  
Vol 38 (2) ◽  
pp. 177-183 ◽  
Author(s):  
Witold Mikulski
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Harmful Effect ◽  
Test Chamber ◽  
Acoustic Energy ◽  
Acoustic Properties ◽  
Sound Absorption Coefficient ◽  
Frequency Range ◽  
Absorbing Materials ◽  
Method Of Measurement

Abstract Sound absorption coefficient is a commonly used parameter to characterize the acoustic properties of sound absorbing materials. It is defined within the frequency range of 100-5 000 Hz. In the industrial conditions, many appliances radiating acoustic energy of the frequency range of above 5000 Hz are used and at the same time it is known that a noise within the frequency range of 5 000-50 000 Hz can have a harmful effect on people,hence there is a need to define the coefficient in this frequency range. The article presents a proposal for a method of measurement of the sound absorption coefficient of materials in the frequency range from 5 000 Hz to 50 000 Hz. This method is a modification of the reverberation method with the use of interrupted noise.

scholarly journals SOUND ABSORPTION OF SOUND SUPRESSING LIGHTWEIGHT STRUCTURED PANELS

Akustika ◽  
2019 ◽  
Vol 34 ◽  
pp. 40-43
Author(s):  
Valery Murzinov ◽  
Pavel Murzinov ◽  
Sergey Popov ◽  
Julia Taratinova
Keyword(s):  
Absorption Coefficient ◽  
Surface Density ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Sound Insulation ◽  
Acoustic Characteristics ◽  
Absorbing Materials

Description of the effective soundproofing panel is presented. For this panel, the ratio of acoustic characteristics and surface density exceeds many modern sound insulation and sound absorbing materials and structures. This article is devoted to modeling the sound absorption coefficient of the soundproof panel. The article presents formulas for determining the coefficient of sound absorption. Construction of a sound suppressed lightweight structured panel (SSLSP) developed by the authors is shown. Comparison of the effectiveness of the SSLSP panel and modern sound-proof materials is shown.

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