A Finite Difference Method for Predicting the Sound Absorption Coefficient of a Fibrous Sample in a Standing Wave Tube

1999 ◽  
Vol 30 (9) ◽  
pp. 29-32
Author(s):  
Antonio Uris ◽  
Jesus Alba ◽  
Jaime Ramis ◽  
Francisco Cervera
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Absorption Coefficient ◽  
Standing Wave ◽  
Difference Method ◽  
Sound Absorption ◽  
Sound Absorption Coefficient ◽  
Wave Tube ◽  
Standing Wave Tube

Fabrication and Sound Absorption Properties of Porous Fe0.2(Co20Ni80)0.8 Alloy Microfibers

2012 ◽  
Vol 538-541 ◽  
pp. 2220-2223
Author(s):  
Xiang Qian Shen ◽  
Hong Bo Liu ◽  
Qing Rong Liang ◽  
Xin Chun Yang
Keyword(s):  
Absorption Coefficient ◽  
Sound Absorption ◽  
Transformation Process ◽  
Sound Absorption Coefficient ◽  
Wave Tube ◽  
Absorption Properties ◽  
Thick Sample ◽  
Noise Absorption ◽  
Reduction Coefficient ◽  
Standing Wave Tube

The porous nanocrystalline Fe0.2(Co20Ni80)0.8 alloy microfibers with diameters of 2-4 μm have been prepared by the citrate-gel and phase transformation process. The sound absorption coefficient for microfibers samples is measured by the standing wave tube method and it is is over 0.8 for the 15 mm thick sample at the frequency range of 2300-6000 Hz, which is extended to 600-6300 Hz for the 40 mm thick sample. The band width with the sound absorption coefficient above 0.6 is wider than 4300 Hz for the 15 mm thick sample and 5800 Hz for the 40 mm thick sample. For the 40 mm thick sample, the maximum absorption coefficient, noise absorption coefficient, noise reduction coefficient and half-width of the absorption peak are 0.99, 0.59, 0.64 and 5828 Hz, respectively. These microfibers are promising advanced acoustic absorbers.

Research of Possibilities of Using the Recycled Materials Based on Rubber and Textiles Combined with Vermiculite Material in the Area of ​​Noise Reduction

2014 ◽  
Vol 1001 ◽  
pp. 171-176 ◽  
Author(s):  
Pavol Liptai ◽  
Marek Moravec ◽  
Miroslav Badida
Keyword(s):  
Absorption Coefficient ◽  
Standing Wave ◽  
Sound Pressure Level ◽  
Sound Absorption ◽  
Sound Pressure ◽  
Sound Level ◽  
Pressure Level ◽  
Sound Absorption Coefficient ◽  
Physical Parameters ◽  
Materials Research

This paper describes possibilities in the use of recycled rubber granules and textile materials combined with vermiculite panel. The aim of the research is the application of materials that will be absorbing or reflecting sound energy. This objective is based on fundamental physical principles of materials research and acoustics. Method of measurement of sound absorption coefficient is based on the principle of standing wave in the impedance tube. With a sound level meter is measured maximum and minimum sound pressure level of standing wave. From the maximum and minimum sound pressure level of standing wave is calculated sound absorption coefficient αn, which can take values from 0 to 1. Determination of the sound absorption coefficient has been set in 1/3 octave band and in the frequency range from 50 Hz to 2000 Hz. In conclusion are proposed possibilities of application of these materials in terms of their mechanical and physical parameters.

A New Method to Measure the Absorption Coefficient of the Automotive Driving Room Based on the Sound Pressure Delaying

2011 ◽  
Vol 415-417 ◽  
pp. 1350-1354
Author(s):  
Cong Yun Zhu ◽  
Jian Ru Shi ◽  
Shu Feng Yang
Keyword(s):  
Absorption Coefficient ◽  
Standing Wave ◽  
Sound Pressure ◽  
Measurement Methods ◽  
The Other ◽  
New Method ◽  
Wave Tube ◽  
Absorption Function ◽  
Equal Distance ◽  
Standing Wave Tube

Absorption coefficient is an important parameter of the absorption function of the absorption material. Traditional measurement methods of absorption coefficient are standing wave tube and reverberation which have some shortcomings. In this paper, phase of the sound pressure measured by two equal distance microphones placed in the front of the absorption material is delayed in order to attain the absorption coefficient. At the last, an experiment for one absorption material is carried out, the experiment results compare with the results of the other methods above mentioned that denotes that the theory is correct and practicable.

The Research and Application on Computational Methods in Fluid Dynamics

2011 ◽  
Vol 317-319 ◽  
pp. 807-810
Author(s):  
Ke Qin Su ◽  
Ya Wei Wang ◽  
Jian Ping Wang
Keyword(s):  
Fluid Dynamics ◽  
Shock Wave ◽  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Flux Vector ◽  
Wave Tube ◽  
Flux Vector Splitting ◽  
Nnd Scheme ◽  
The Difference

The NND scheme based on Van Leer flux vector splitting is presented. The flow field of shock wave tube is calculated by the difference method presented in this paper, which shows that the presented finite difference method has fine calculation precision and efficiency, and could capture shock automatically.

Sound Absorption Properties of Polyester Fibers Needle-Punched Nonwoven Fabrics

2011 ◽  
Vol 332-334 ◽  
pp. 1300-1303
Author(s):  
Ke Tian Guan ◽  
Xu Pin Zhuang ◽  
Xiao Ning Jiao ◽  
Men Qin Li ◽  
Hong Jun Li ◽  
...  
Keyword(s):  
Surface Structure ◽  
Standing Wave ◽  
Sound Absorption ◽  
Fiber Diameter ◽  
Absorption Property ◽  
Wave Tube ◽  
Absorption Properties ◽  
Nonwoven Fabrics ◽  
Polyester Fibers ◽  
Standing Wave Tube

Polyester fiber needle-punched nonwovens with different structures were manufactured and their sound absorption properties were examined using the standing wave tube method. The results show that the sound absorption property of the nonwovens depends on their thickness, needling intensity, fiber diameter and surface structure.

Development of a Standing Wave-Tube System for Acoustical Property Measurement of Sound Absorption Materials Used on Vehicles

2011 ◽  
Vol 474-476 ◽  
pp. 1146-1150
Author(s):  
Yan Song Wang ◽  
Jian Peng Zhou ◽  
Yan Feng Xing
Keyword(s):  
Standing Wave ◽  
Sound Absorption ◽  
Ratio Method ◽  
Wave Tube ◽  
Tube System ◽  
Signal Amplifier ◽  
Acoustical Property ◽  
Property Measurement ◽  
Standing Wave Tube ◽  
Materials Used

A standing wave-tube system for acoustical property measurement of vehicle-used sound absorption materials is developed in this paper. Theoretically, the standing wave ratio method and the two-cavity method with two-microphone configurations are combined and applied for calculating some acoustical parameters, such as sound absorption ratio, reflection coefficient, characteristic impedance, propagation constant, of a sample material. Based on the combined method, the standing wave-tube system including two microphones, an A/D board, a signal amplifier, a DSP computer and a set of software is carefully designed and performed. The verification results suggest that the newly designed system is accurate for acoustical property measurement of the materials used on vehicles. It can be directly used for selecting noise-control materials in vehicle acoustical designs.

A New Method to Measure the Absorption Coefficient Based on the Sound Pressure Delaying

2013 ◽  
Vol 834-836 ◽  
pp. 1156-1160
Author(s):  
Da Yu Huang
Keyword(s):  
Absorption Coefficient ◽  
Standing Wave ◽  
Sound Pressure ◽  
Measurement Methods ◽  
Reverberation Time ◽  
Wave Tube ◽  
Absorption Function ◽  
Equal Distance ◽  
Key Words Absorption ◽  
Standing Wave Tube

Absorption coefficient is an important parameter of the absorption function of the absorption material. Traditional measurement methods of absorption coefficient are standing wave tube and reverberation which have some shortcomings. In this paper, phase of the sound pressure measured by two equal distance microphones placed in the front of the absorption material is delayed in order to attain the absorption coefficient. At the last, an experiment for one absorption material is carried out, the experiment results compare with the results of the other methods above mentioned that denotes that the theory is correct and practicable. Key words: absorption material standing wave reverberation time delaying

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