Nearfield acoustic holography in a moving medium based on particle velocity input using nonsingular propagator

2021 ◽  
Author(s):  
Bi-Chun Dong ◽  
Run-Mei Zhang ◽  
Bin Yuan ◽  
Chuan-Yang Yu
Keyword(s):  
Particle Velocity ◽  
Flow Direction ◽  
Sound Field ◽  
Singular Problem ◽  
Moving Medium ◽  
Acoustic Holography ◽  
Sound Sources ◽  
Sound Field Reconstruction ◽  
Velocity Input ◽  
Nearfield Acoustic Holography

Abstract Nearfield acoustic holography in a moving medium is a technique which is typically suitable for sound sources identification in a flow. In the process of sound field reconstruction, sound pressure is usually used as the input, but it may contain considerable background noise due to the interactions between microphones and flow moving at a high velocity. To avoid this problem, particle velocity is an alternative input, which can be obtained by using Laser Doppler Velocimetry in a non-intrusive way. However, there is a singular problem in the conventional propagator relating the particle velocity to the pressure, and it could lead to significant errors or even false results. In view of this, in this paper nonsingular propagators are deduced to realize accurate reconstruction in both cases that the hologram is parallel to and perpendicular to the flow direction. The advantages of the proposed method are analyzed, and simulations are conducted to verify the validation. The results show that the method can overcome the singular problem effectively, and the reconstruction errors are at a low level for different flow velocities, frequencies, and signal-to-noise ratios.

Equivalent Source Method-Based Nearfield Acoustic Holography in a Moving Medium

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Chuan-Xing Bi ◽  
Bi-Chun Dong ◽  
Xiao-Zheng Zhang ◽  
Yong-Bin Zhang
Keyword(s):  
Particle Velocity ◽  
Analytical Relationship ◽  
Moving Medium ◽  
Acoustic Holography ◽  
Sound Sources ◽  
Equivalent Source ◽  
Source Method ◽  
Velocity Input ◽  
Equivalent Source Method ◽  
Nearfield Acoustic Holography

To identify sound sources situated in a fluid flow, an equivalent source method (ESM)-based nearfield acoustic holography (NAH) in a moving medium is proposed, and two types of acoustic inputs, pressure and particle velocity, are considered. In particular, an analytical relationship between the particle velocity perpendicular to the flow direction and the equivalent source strength is deduced, which makes it possible to realize the reconstruction with particle velocity input. Compared to the planar NAH in a moving medium, the proposed method is applicable to sound sources with more complicated geometries. Numerical simulations with sound sources distributed over two types of geometries including planar geometry and nonplanar one are conducted to test the performances of the proposed method. The results indicate that the proposed method provides satisfactory reconstructed results whatever with pressure input or with particle velocity input, and it is valid and robust over a wide range of flow velocities and frequencies and under different levels of background noise.

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.

Patch nearfield acoustic holography in a moving medium

2014 ◽  
Vol 86 ◽  
pp. 71-79 ◽  
Author(s):  
Bi-Chun Dong ◽  
Chuan-Xing Bi ◽  
Xiao-Zheng Zhang ◽  
Yong-Bin Zhang
Keyword(s):  
Moving Medium ◽  
Acoustic Holography ◽  
Nearfield Acoustic Holography

Real-time nearfield acoustic holography in a uniformly moving medium

2017 ◽  
Vol 410 ◽  
pp. 364-377 ◽  
Author(s):  
Bi-Chun Dong ◽  
Chuan-Xing Bi ◽  
Xiao-Zheng Zhang ◽  
Yong-Bin Zhang
Keyword(s):  
Real Time ◽  
Moving Medium ◽  
Acoustic Holography ◽  
Nearfield Acoustic Holography

An Introduction to Virtual Phased Arrays for Beamforming Applications

2015 ◽  
Vol 39 (1) ◽  
pp. 81-88 ◽  
Author(s):  
Daniel Fernández Comesana ◽  
Keith R. Holland ◽  
Dolores García Escribano ◽  
Hans-Elias de Bree
Keyword(s):  
Sound Localization ◽  
Relative Phase ◽  
Phased Arrays ◽  
Sound Field ◽  
Microphone Arrays ◽  
Acoustic Sensor ◽  
Frequency Range ◽  
Acoustic Holography ◽  
Sound Sources ◽  
Single Sensor

Abstract Sound localization problems are usually tackled by the acquisition of data from phased microphone arrays and the application of acoustic holography or beamforming algorithms. However, the number of sensors required to achieve reliable results is often prohibitive, particularly if the frequency range of interest is wide. It is shown that the number of sensors required can be reduced dramatically providing the sound field is time stationary. The use of scanning techniques such as “Scan & Paint” allows for the gathering of data across a sound field in a fast and efficient way, using a single sensor and webcam only. It is also possible to characterize the relative phase field by including an additional static microphone during the acquisition process. This paper presents the theoretical and experimental basis of the proposed method to localise sound sources using only one fixed microphone and one moving acoustic sensor. The accuracy and resolution of the method have been proven to be comparable to large microphone arrays, thus constituting the so called “virtual phased arrays”.

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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