scholarly journals Sound field separation technique and its applications in near-field acoustic holography

2005 ◽  
Vol 54 (2) ◽  
pp. 789
Author(s):  
Yu Fei ◽  
Chen Jian ◽  
Li Wei-Bing ◽  
Chen Xin-Zhao
Keyword(s):  
Near Field ◽  
Sound Field ◽  
Separation Technique ◽  
Acoustic Holography ◽  
Field Separation

Development of Near-Field Acoustical Holograph and its Review

2014 ◽  
Vol 971-973 ◽  
pp. 1598-1601
Author(s):  
Xu Liu ◽  
Xiao Qin Liu ◽  
Chang Liu
Keyword(s):  
Near Field ◽  
Sound Field ◽  
Separation Technique ◽  
Acoustic Holography ◽  
Noise Sources ◽  
Engineering Applications ◽  
Powerful Technique ◽  
Experiment And Simulation ◽  
Acoustical Holography ◽  
Field Separation

Near-field acoustic holography (NAH) is a powerful technique for identifying noise sources and visualizing acoustic field.The theory and algorithm of NAH techniques are introduced , and it is proved by experiment and simulation. The researches on near field acoustical holography (NAH) are reviewed，including the sound field separation technique and Patch NAH technique arisen in recent years.The difficulties in NAH and research on current situations are discussed , Finally,some engineering applications are introduced by detailed examples.

scholarly journals The principle of statistically optimal planar near-field acoustical holography and the sound field separation technique

2005 ◽  
Vol 54 (3) ◽  
pp. 1253 ◽  
Author(s):  
Li Wei-Bing ◽  
Chen Jian ◽  
Yu Fei ◽  
Bi Chuan-Xing ◽  
Chen Xin-Zhao
Keyword(s):  
Near Field ◽  
Sound Field ◽  
Separation Technique ◽  
Acoustical Holography ◽  
Field Separation

Near Field Acoustic Holography for Cyclostationary Sound Field and its Partial Source Decomposition Procedure

2005 ◽  
Vol 127 (6) ◽  
pp. 542-546 ◽  
Author(s):  
Quan Wan ◽  
W. K. Jiang
Keyword(s):  
Principal Component Analysis ◽  
Sound Pressure ◽  
Near Field ◽  
Sound Field ◽  
Principal Component ◽  
Acoustic Holography ◽  
Sound Sources ◽  
Decomposition Procedure ◽  
Spectrum Density ◽  
Simulation Results

The cyclostationary near field acoustic holography (NAH) technique is proposed to overcome the limitations of the current NAH in analyzing cyclostationary sound field. The proposed technique adopts the cyclic spectrum density as the reconstructed physical quantity, instead of the spectrum of sound pressure. Moreover, introducing the principal component analysis into the technique, a partial source decomposition procedure is suggested to decompose the sound field radiated by multiple sound sources into some incoherent partial fields. More information about cyclostationary sound field can be shown clearly on the hologram of the proposed technique than NAH can, which is validated by the simulation results.

Near-Field Acoustic Holography of Cyclostationary Sound Field

2013 ◽  
Vol 631-632 ◽  
pp. 1318-1323
Author(s):  
Min Peng
Keyword(s):  
Time Series ◽  
Sound Pressure ◽  
Near Field ◽  
Sound Field ◽  
Rotating Machinery ◽  
Stationary Field ◽  
Acoustic Holography ◽  
Complex Sound ◽  
Radiated Sound ◽  
Slice Method

The radiated sound field of rotating machinery or reciprocating machinery has a significant periodically time-variant nature. This is a kind of non-stationary sound field and called cyclostationary sound field. In the conventional planar near-field acoustic holography(PNAH), this kind of sound field is treated as stationary field, so the information relating to the change of frequency with time will be loss inevitably. In this article, the cyclic spectral density(CSD) instead of the complex sound pressure was adopted as reconstructing physical quantity in the PNAH, and the cyclostationary PNAH(CPNAH) technique was proposed. Meanwhile, focusing on the calculation complex of CSD and the accuracy of the cyclic nature extracted, the gathering slice method of CSD was proposed by referring time aliasing methods on time series. The experiment results illustrate that the cyclic nature of cyclostationary sound field may be extracted directly and the location of the source determined exactly as well.

Study of Spherical Near-Field Acoustic Holography with Rigid Spherical Microphone Array

2013 ◽  
Vol 546 ◽  
pp. 156-163
Author(s):  
Xin Guo Qiu ◽  
Ming Zong Li ◽  
Huan Cai Lu ◽  
Wei Jiang
Keyword(s):  
Sound Source ◽  
Microphone Array ◽  
Near Field ◽  
Sound Field ◽  
Acoustic Holography ◽  
Real Situation ◽  
Helmholtz Equations ◽  
Sound Sources ◽  
Array Configuration ◽  
Sphere Radius

The aim of this paper is to investigate the impacts of various parameters of rigid spherical microphone array in detecting and locating interior sound source. Helmholtz Equations are adopted to express the sound field produced by the incident field and scattered field. The gradient of the pressure is zero at the surface for the sphere is rigid. Both the incident and scattered coefficient could be obtained by solving the Helmholtz Equation using the boundary condition. Then the interior sound field could be detected and located on with the methodology of spherical near-field acoustic holography (SNAH). This study is developed in two aspects，one is configuring the microphone in various distribution in the same sphere radius, and the other one is changing the radius of sphere array. Numerical simulations are carried out to determine the optimum microphone array configuration and structure parameters. One, two, and three sound sources are arranged respectively in different displacement to the sphere center and in different angle direction to simulate the real situation. During the experiments, Omni-directional speakers and beeps are adopted as sound sources. The result shows that the method to detect and locate sound source in interior sound field is valid.

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