A sound field separation technique based on measurements with pressure-velocity probes

Zhang, Yongbin; Xinzhao, Chen; Jacobsen, Finn

doi:10.1121/1.3127128

Cited by 30 publications

(9 citation statements)

References 10 publications

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“…Substituting eqs. (5) and (6) into eq. (3), the pressure P 11 produced by the target source on the surface H 1 can be solved as:…”

Section: Basic Theorymentioning

confidence: 98%

“…Many FSTs have been developed in the past years. They are based on different methods, including the spatial Fourier transform method [2,3], the statistically optimal NAH (SONAH) [4,5], the hybrid NAH technique [6], the boundary element method (BEM) [7], and the equivalent source method (ESM) [8]. The FST allows the existence of disturbing sources or reflecting surfaces on the opposite side of the hologram surface.…”

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confidence: 99%

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Patch nearfield acoustic holography combined with sound field separation technique applied to a non-free field

Jing

Zhang

et al. 2014

Sci. China Phys. Mech. Astron.

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The conventional nearfield acoustic holography (NAH) is usually based on the assumption of free-field conditions, and it also requires that the measurement aperture should be larger than the actual source. This paper is to focus on the problem that neither of the above-mentioned requirements can be met, and to examine the feasibility of reconstructing the sound field radiated by partial source, based on double-layer pressure measurements made in a non-free field by using patch NAH combined with sound field separation technique. And also, the sensitivity of the reconstructed result to the measurement error is analyzed in detail. Two experiments involving two speakers in an exterior space and one speaker inside a car cabin are presented. The experimental results demonstrate that the patch NAH based on single-layer pressure measurement cannot obtain a satisfied result due to the influences of disturbing sources and reflections, while the patch NAH based on double-layer pressure measurements can successfully remove these influences and reconstruct the patch sound field effectively. nearfield acoustic holography, sound field separation, equivalent source method PACS number(s): 43.60.Sx, 43.60.Pt, 43.20.Ye Citation: Bi C X, Jing W Q, Zhang Y B, et al. Patch nearfield acoustic holography combined with sound field separation technique applied to a non-free field.Since its first appearance in 1980 [1], nearfield acoustic holography (NAH) has been proven to be a powerful technique for noise source identification and sound field visualization. In the conventional NAH, there are two requirements. The first is the measurement should be done under free-field conditions, i.e., all the sources should be located on one side of the hologram surface. The second is the measurement aperture should be larger than the actual source. However, in practical applications, it is very difficult to guarantee that the sound field is free, due to the influences of disturbing sources or reflections. And, it is often impossible to measure such a large aperture for a large vibrating structure. Sound field separation technique (FST) has been proven to be effective in dealing with the first problem. Using the FST, the conventional NAH can then be used to reconstruct the sound field radiated by the target source. Many FSTs have been developed in the past years. They are based on different methods, including the spatial Fourier transform method [2,3], the statistically optimal NAH (SONAH) [4,5], the hybrid NAH technique [6], the boundary element method (BEM) [7], and the equivalent source method (ESM) [8]. The FST allows the existence of disturbing sources or reflecting surfaces on the opposite side of the hologram surface. However, the measurement aperture is still required to be larger than the actual source.Patch NAH, which is capable of reconstructing the sound field radiated by partial source through a "patch" measurement, makes it possible to deal with the second problem. It was originally developed from the conventional NAH by introducing a wav...

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“…Substituting eqs. (5) and (6) into eq. (3), the pressure P 11 produced by the target source on the surface H 1 can be solved as:…”

Section: Basic Theorymentioning

confidence: 98%

mentioning

confidence: 99%

Patch nearfield acoustic holography combined with sound field separation technique applied to a non-free field

Jing

Zhang

et al. 2014

Sci. China Phys. Mech. Astron.

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“…The spatial Fourier transform method-based SFST (Refs,(4)(5)(6)(7)(8)(9)(10), which has generally been used for measuring reflection coefficients [4][5][6][7][8] and separating incident and scattered fields, 9,10 was developed by Hallman and Bolton 11,12 to perform NAH in reflective environments, and by Williams 13 and Yu et al 14 to remove the effect of a disturbing source in NAH applications. Statistically optimized near-field acoustical holography (SONAH) has also been implemented by using a two-layer handheld array, 15,16 an array of pressure-velocity probes, [17][18][19] and a double-layer velocity transducer array. 20 The boundary element method can also be based on using a double-layer array 21,22 or Cauchy data.…”

Section: Introductionmentioning

confidence: 99%

An equivalent source technique for recovering the free sound field in a noisy environment

Bolton²

2012

The Journal of the Acoustical Society of America

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In previous studies, a sound field separation technique based on the equivalent source method (ESM) was successfully applied to separate the incoming and outgoing fields composing a non-free field. However, if the incoming wave is scattered by the source surface, the outgoing field is not the field that would be generated by the source in a free field. The object of the present work was to provide an equivalent source technique that allows the recovery of that free field in a noisy environment. In this approach, the incoming and outgoing fields, including the scattered and directly radiated fields on the measurement surface, are separated to obtain the free-field pressure that would be radiated by the source in an anechoic environment. The recovered free-field pressure is then used to reconstruct the whole free field of the source by using near-field acoustical holography based on the ESM, which makes the results equivalent to those that could be obtained from a free-field measurement. A theoretical description of the technique is given first, and then three numerical cases are investigated to demonstrate the ability of the proposed method.

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“…As one of the relatively mature sound field imaging techniques, the near-field acoustical holography (NAH) [1][2][3] can realize a non-contact measurement near the sound sources. This technique allows one to reconstruct or predict the radiated harmonic acoustic field in the frequency domain [4][5][6][7]. For the purpose of inversely studying the transient acoustic problems [8,9] in the time domain, some timedomain NAH (TNAH) methods [10][11][12][13][14] have been developed during the last two decades.…”

Section: Introductionmentioning

confidence: 99%

An interpolated time-domain equivalent source method for modeling transient acoustic radiation over a mass-like plane based on the transient half-space Green’s function

et al. 2014

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A sound field separation technique based on measurements with pressure-velocity probes

Cited by 30 publications

References 10 publications

Patch nearfield acoustic holography combined with sound field separation technique applied to a non-free field

Patch nearfield acoustic holography combined with sound field separation technique applied to a non-free field

An equivalent source technique for recovering the free sound field in a noisy environment

An interpolated time-domain equivalent source method for modeling transient acoustic radiation over a mass-like plane based on the transient half-space Green’s function

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