Variations in Sound Absorption Coefficients as Obtained by the Reverberation Chamber Method

1938 ◽  
Vol 9 (3) ◽  
pp. 234-243 ◽  
Author(s):  
R. M. Morris ◽  
G. M. Nixon ◽  
J. S. Parkinson
Keyword(s):  
Sound Absorption ◽  
Absorption Coefficients ◽  
Reverberation Chamber ◽  
Chamber Method

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.

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

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1091 ◽  
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.

scholarly journals Preparation and Characterization of Gradient Compressed Porous Metal for High-Efficiency and Thin-Thickness Acoustic Absorber

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1413 ◽  
Author(s):  
Xiaocui Yang ◽  
Xinmin Shen ◽  
Panfeng Bai ◽  
Xiaohui He ◽  
Xiaonan Zhang ◽  
...  
Keyword(s):  
Sound Absorption ◽  
High Efficiency ◽  
Structural Parameters ◽  
Porous Metal ◽  
Theoretical Models ◽  
Absorption Efficiency ◽  
Total Thickness ◽  
Porous Metals ◽  
Absorption Coefficients ◽  
Optimal Average

Increasing absorption efficiency and decreasing total thickness of the acoustic absorber is favorable to promote its practical application. Four compressed porous metals with compression ratios of 0%, 30%, 60%, and 90% were prepared to assemble the four-layer gradient compressed porous metals, which aimed to develop the acoustic absorber with high-efficiency and thin thickness. Through deriving structural parameters of thickness, porosity, and static flow resistivity for the compressed porous metals, theoretical models of sound absorption coefficients of the gradient compressed porous metals were constructed through transfer matrix method according to the Johnson–Champoux–Allard model. Sound absorption coefficients of four-layer gradient compressed porous metals with the different permutations were theoretically analyzed and experimentally measured, and the optimal average sound absorption coefficient of 60.33% in 100–6000 Hz was obtained with the total thickness of 11 mm. Sound absorption coefficients of the optimal gradient compressed porous metal were further compared with those of the simple superposed compressed porous metal, which proved that the former could obtain higher absorption efficiency with thinner thickness and fewer materials. These phenomena were explored by morphology characterizations. The developed high-efficiency and thin-thickness acoustic absorber of gradient compressed porous metal can be applied in acoustic environmental detection and industrial noise reduction.

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

scholarly journals COMPARATIVE ANALYSIS OF SOUND SUPRESSING LIGHTWEIGHT STRUCTURED PANELS AND MODERN NOISE PROTECTION MEANS

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 30-35
Author(s):  
Valery Murzinov ◽  
Pavel Murzinov ◽  
Irina Ivanovna
Keyword(s):  
Comparative Analysis ◽  
Sound Absorption ◽  
Absorption Coefficients ◽  
Acoustic Insulation ◽  
Materials Used ◽  
And Control

This article provides an overview of modern soundproof materials and structures used for acoustic insulation. Presently, we can find plenty of such noise insulation and sound absorption materials. One of the popular means to reduce noise and control sound today is the acoustic panels able to suppress and absorb different sounds. The article also analyses the effectiveness of acoustic and sound protection materials used in the industrial sphere. The comparative analysis of the sound protection and absorption effectiveness is carried out using sound absorption coefficients. It also presents the construction of a sound suppressing lightweight structured panel designed by the authors. The authors noted that these panels have better characteristics in comparison with other modern sound protection materials.

scholarly journals Effects of heat treatment on sound absorption coefficients in nanosilver‐impregnated and normal solid woods

2016 ◽  
Vol 11 (4) ◽  
pp. 365-369 ◽  
Author(s):  
Ayoub Esmailpour ◽  
Hamid Reza Taghiyari ◽  
Habib Zolfaghari
Keyword(s):  
Heat Treatment ◽  
Sound Absorption ◽  
Absorption Coefficients
Sign in / Sign up

Export Citation Format

Share Document