Small Reverberation Chamber for Measuring the Sound Absorption of Materials at High Frequencies

1955 ◽  
Vol 27 (5) ◽  
pp. 1003-1003
Author(s):  
D. E. Bishop
Keyword(s):  
Sound Absorption ◽  
Reverberation Chamber ◽  
High Frequencies

Absorption Characteristics of Suspended Absorbers

1994 ◽  
Vol 1 (4) ◽  
pp. 279-286
Author(s):  
L. Kortchmar ◽  
M. A. Nabuco De Araujo ◽  
S.N.Y. Gerges
Keyword(s):  
Sound Absorption ◽  
Sound Field ◽  
Reverberation Chamber ◽  
High Frequencies ◽  
Statistical Precision ◽  
Air Space ◽  
Absorption Characteristics

The question of the arrangement of sound absorbers has been under study for some time. In our approach we conducted a sequence of experiments in a reverberation chamber to determine the optimal sound absorption for different configurations of suspended absorbers using various air spaces and a central dividing panel between them. The results obtained were compared with measurements of the panels, tested against a solid backing as specified in ISO-R-354. It is shown that a porous absorber is more efficient at high frequencies if it is suspended in the sound field rather than against a solid backing. It was also found that the efficiency of an air space between the two porous sheets that compose a suspended absorber is moderately increased when a central divider is used. The statistical precision of the test was also investigated.

scholarly journals Методы определения характеристик звукопоглощения строительных материалов и звукоизоляции конструкций (обзор)

2020 ◽  
Vol 45 (4) ◽  
Author(s):  
Keyword(s):  
Noise Reduction ◽  
Sound Absorption ◽  
Building Materials ◽  
Developed Countries ◽  
Reduction Factor ◽  
Sound Insulation ◽  
Reverberation Chamber ◽  
Normative Documents ◽  
Urban Conditions ◽  
First Time

Исследование акустических характеристик строительных материалов и конструкций необходимо для комфортной жизни людей в городских условиях. Несмотря на то что в нормативных документах развитых государств есть ряд методов их определения, единого понимания самих характеристик и путей их адекватного определения до сих пор нет. В настоящей работе мы попытались систематизировать и дать критический обзор нормативных документов, содержащих методы определения звукопоглощающих свойств материалов и звукоизоляционных характеристик конструкций. Впервые выявлены присущие разным методам закономерности определения характеристик звукопоглощения и звукоизоляции. Определены наиболее характерные показатели звукопоглощения. Произведено ранжирование по коэффициенту уменьшения шума NRC наиболее часто применяемых строительных материалов. Названы области применения рассматриваемых методик, проанализированы их преимущества и ограничения. Ключевые слова: коэффициент уменьшения шума, звукопоглотитель, импедансная труба, реверберационная камера The study of the acoustic characteristics of building materials and structures is necessary for provision of comfortable life of people in urban conditions. Despite the fact that in the normative documents of developed countries there are a number of methods for their determination, there is still no common understanding of the characteristics themselves and the ways of their adequate determination. In this work we tried to systematize and give a critical review of regulatory documents containing the methods for determining the sound-absorbing properties of materials and the sound-insulating characteristics of structures. For the first time the regularities in determination the characteristics of sound absorption and sound insulation inherent in different methods have been revealed. The most characteristic indicators of sound absorption have been determined. The ranking of the most commonly used building materials was made according to the noise reduction factor (NRC). The areas of application of the considered methods are presented, their advantages and limitations are analyzed. Keywords: noise reduction factor, sound absorber, impedance tube, reverberation chamber

Sound absorption in a scale model reverberation chamber

2002 ◽  
Vol 112 (5) ◽  
pp. 2397-2397
Author(s):  
Ranny Nascimento ◽  
Moyses Zindeluk ◽  
Jose Flavio Feiteira
Keyword(s):  
Sound Absorption ◽  
Scale Model ◽  
Reverberation Chamber

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.

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.

Modelling sound absorption properties for recycled polyethylene terephthalate-based material using Gaussian regression

2020 ◽  
pp. 1351010X2093313 ◽  
Author(s):  
Gino Iannace ◽  
Giuseppe Ciaburro
Keyword(s):  
Polyethylene Terephthalate ◽  
Sound Absorption ◽  
Acoustic Properties ◽  
Excellent Performance ◽  
Absorption Properties ◽  
High Frequencies ◽  
Plastic Materials ◽  
Recycled Polyethylene ◽  
The World ◽  
Gaussian Regression

Plastic is widely used all over the world and its production has been increasing continuously in recent years. But plastic presents significant problems about its end-of-life given its important environmental impact. These problems impose recycling policies which provide for the collection and recycling of plastic materials. In this work, the acoustic properties of a recycled polyethylene terephthalate-based material were analyzed. The material showed good sound-absorbing characteristics, especially at high frequencies. In addition, a numerical model based on the Gaussian regression was developed to simulate the sound absorption coefficient of the material. The model returned an R-Squared value of 0.97 demonstrating excellent performance.

The Process Development for Sound Absorption Design of Non-Woven Car Mat

2020 ◽  
Vol 305 ◽  
pp. 43-48
Author(s):  
Un Hwan Park ◽  
Jun Hyeok Heo ◽  
In Sung Lee ◽  
Dae Kyu Park
Keyword(s):  
Absorption Coefficient ◽  
Physical Properties ◽  
Sound Absorption ◽  
Process Development ◽  
Sound Absorption Coefficient ◽  
Development Effort ◽  
Reverberation Chamber ◽  
Impedance Tube ◽  
Impedance Tubes ◽  
Automotive Interior

Automotive interior material with consists of several material layers has the sound-absorbing function. It is difficult to predict sound absorbing coefficient because of several material layers. So, many experimental tuning is required to achieve the target of sound absorption. Therefore, while the car interior materials are developed, a lot of time and money is spent. In this study, we present the method to predict the sound absorbing performance of the material with multi-layer using physical properties of each material. The properties are predicted by foam-X software using sound absorption coefficient data measured by impedance tube. And we will compare and analyze the predicted sound absorption coefficient with the data measured by scaled reverberation chamber and impedance tubes for a prototype. If the method is used instead of experimental tuning in the development of car interior material, the time and money can be saved. And then, the development effort can be is reduced because it can be optimized by simulation.

scholarly journals A Basic Study on a Rectangular Plane Space Sound Absorber Using Permeable Membranes

2019 ◽  
Vol 11 (7) ◽  
pp. 2185 ◽  
Author(s):  
Sakagami ◽  
Okuzono ◽  
Somatomo ◽  
Funahashi ◽  
Toyoda
Keyword(s):  
Sound Absorption ◽  
Woven Fabrics ◽  
Absorption Coefficients ◽  
Basic Study ◽  
Low Frequencies ◽  
Permeable Membrane ◽  
High Frequencies ◽  
Single Leaf ◽  
A Value ◽  
Plane Space

In this communication, the sound absorption characteristics of rectangular-shaped plane space sound absorbers without any backing structure using permeable membranes (PMs) are measured by reverberation room method. First, three types of PMs, in this study woven fabrics, are selected with different flow resistances and surface densities. They are prepared in the plane rectangular-shaped space absorbers of two different sizes. The measured results are discussed through comparison with the existing theoretical and measured results for absorbers of the other shapes or configurations. The present results and discussion demonstrate that the reverberation absorption coefficients of the proposed absorbers are low at low frequencies and converge to a moderately high value at high frequencies. Especially, ones with higher flow resistance than the air impedance converge to a value greater than 0.5, which is a theoretically estimated maximum absorption coefficient of infinite single-leaf PM. This is inferred to be attributed mainly to area effect. From these results the proposed absorbers can be used effectively despite of their very simple structure. Also it is found that the proposed absorber can offer higher sound absorption than permeable membrane absorbers of other shapes or configuration. Regarding the effect of the size, the absorbers of smaller size offer higher absorption coefficients regardless of material properties of the PMs used in the experiments.

scholarly journals Angle-Dependent Absorption of Sound on Porous Materials

Acoustics ◽  
2020 ◽  
Vol 2 (4) ◽  
pp. 753-765
Author(s):  
Jose Cucharero ◽  
Tuomas Hänninen ◽  
Tapio Lokki
Keyword(s):  
Sound Absorption ◽  
Glass Wool ◽  
Room Acoustics ◽  
Sound Waves ◽  
Absorption Coefficients ◽  
Reverberation Chamber ◽  
Impedance Tube ◽  
Material Development ◽  
Dependent Absorption ◽  
Good Agreement

Sound-absorbing materials are usually measured in a reverberation chamber (diffuse field condition) or in an impedance tube (normal sound incidence). In this paper, we show how angle-dependent absorption coefficients could be measured in a factory-type setting. The results confirm that the materials have different attenuation behavior to sound waves coming from different directions. Furthermore, the results are in good agreement with sound absorption coefficients measured for comparison in a reverberation room and in an impedance tube. In addition, we introduce a biofiber-based material that has similar sound absorption characteristics to glass-wool. The angle-dependent absorption coefficients are important information in material development and in room acoustics modeling.

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