Cross-spectral method of measuring acoustic intensity without error caused by instrument phase mismatch

Chung, J. Y.

doi:10.1121/1.382145

Cited by 145 publications

(48 citation statements)

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“…24,25 Unfortunately, most p-p intensity probes are not symmetrical and therefore not suitable for real measurements with the probe reversed. By contrast the MF probe can easily be reversed.…”

Section: Discussionmentioning

confidence: 99%

A comparison of two different sound intensity measurement principles

Jacobsen

Bree

2005

The Journal of the Acoustical Society of America

113

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The dominating method of measuring sound intensity in air is based on the combination of two pressure microphones. However, a sound intensity probe that combines an acoustic particle velocity transducer with a pressure microphone has recently become available. This paper examines, discusses, and compares the two measurement principles with particular regard to the sources of error in sound power determination. It is shown that the phase calibration of intensity probes that combine different transducers is very critical below 500 Hz if the measurement surface is very close to the source under test. The problem is reduced if the measurement surface is moved further away from the source. The calibration can be carried out in an anechoic room.

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Section: Discussionmentioning

confidence: 99%

A comparison of two different sound intensity measurement principles

Jacobsen

Bree

2005

The Journal of the Acoustical Society of America

113

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“…In this case time-averaged intensity ( , ) can be thought of as a statistical function akin to a power spectra (indeed in the two-microphone method it is calculated from a cross-power spectra [16]), only here measuring acoustic power flux density through space instead of power in a 1D signal. Building on this interpretation, the result of incoherent power addition between Φ and Ψ would be + .…”

Section: Acoustic Cross-intensitymentioning

confidence: 99%

An Energy Interpretation of the Kirchhoff-Helmholtz Boundary Integral Equation and its Application to Sound Field Synthesis

Hargreaves¹,

Lam²

2014

Acta Acustica united with Acustica

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Most spatial audio reproduction systems have the constraint that all loudspeakers must be equidistant from the listener, a property which is difficult to achieve in real rooms. In traditional Ambisonics this arises because the spherical harmonic functions, which are used to encode the spatial sound-field, are orthonormal over a sphere and because loudspeaker proximity is not fully addressed. Recently, significant progress to lift this restriction has been made through the theory of sound field synthesis, which formalizes various spatial audio systems in a mathematical framework based on the single layer potential. This approach has shown many benefits but the theory, which treats audio rendering as a sound-soft scattering problem, can appear one step removed from the physical reality and also possesses frequencies where the solution is non-unique. In the time-domain Boundary Element Method approaches to address such non-uniqueness amount to statements which test the flow of acoustic energy rather than considering pressure alone. This paper applies that notion to spatial audio rendering by re-examining the Kirchhoff-Helmholtz integral equation as a wave-matching metric, and suggests a physical interpretation of its kernel in terms of common acoustic power flux density between waves. It is shown that the spherical basis functions (spherical harmonics multiplied by spherical Bessel or Hankel functions) are orthogonal over any arbitrary surface with respect to this metric. Finally other applications are discussed, including design of high-order microphone arrays and the coupling of virtual acoustic models to auralization hardware.

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“…Measurement of the acoustic energy flux 21 can be carried out by using two nearby microphones, [22][23][24] or using devices that contain a microphone and an accelerometer. 25,26 The proposed method for Green's function extraction can be applied to such measurements.…”

Section: Discussionmentioning

confidence: 99%

Extracting the Green’s function from measurements of the energy flux

Snieder

Douma

Vasconcelos

2012

The Journal of the Acoustical Society of America

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Existing methods for Green’s function extraction give the Green’s function from the correlation of field fluctuations recorded at those points. In this work it is shown that the Green’s function for acoustic waves can be retrieved from measurements of the integrated energy flux through a closed surface taken from three experiments where two time-harmonic sources first operate separately, and then simultaneously. This makes it possible to infer the Green’s function in acoustics from measurements of the energy flux through an arbitrary closed surface surrounding both sources. The theory is also applicable to quantum mechanics where the Green’s function can be retrieved from measurement of the flux of scattered particles through a closed surface.

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Cross-spectral method of measuring acoustic intensity without error caused by instrument phase mismatch

Cited by 145 publications

References 0 publications

A comparison of two different sound intensity measurement principles

A comparison of two different sound intensity measurement principles

An Energy Interpretation of the Kirchhoff-Helmholtz Boundary Integral Equation and its Application to Sound Field Synthesis

Extracting the Green’s function from measurements of the energy flux

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