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Planar near-field acoustical holography in a moving medium
Journal of the Acoustical Society of America, 2002Near-field acoustical holography (NAH) is a well-established method to study acoustic radiation near a stationary sound source in a homogeneous, stationary medium. However, the current theory of NAH is not applicable to moving sound sources, such as automobiles and trains.
Richard J, Ruhala, David C, Swanson
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Interior near-field acoustical holography in flight
Journal of the Acoustical Society of America, 2000In this paper boundary element methods (BEM) are mated with near-field acoustical holography (NAH) in order to determine the normal velocity over a large area of a fuselage of a turboprop airplane from a measurement of the pressure (hologram) on a concentric surface in the interior of the aircraft.
Brian H Houston
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Multisource statistically optimized near-field acoustical holography
Journal of the Acoustical Society of America, 2015This paper presents a reduced-order approach to near-field acoustical holography (NAH) that allows the user to account for sound fields generated by multiple spatially separated sources. In this method, an equivalent wave model (EWM) of a given field is formulated to include combinations of planar, cylindrical, spherical, or other elementary wave ...
Kent Gee +2 more
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Regularization methods for near-field acoustical holography
Journal of the Acoustical Society of America, 2001The reconstruction of the pressure and normal surface velocity provided by near-field acoustical holography (NAH) from pressure measurements made near a vibrating structure is a linear, ill-posed inverse problem due to the existence of strongly decaying, evanescentlike waves.
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A one-step patch near-field acoustical holography procedure
Journal of the Acoustical Society of America, 2007When performing holography measurements over a limited area of a source, the hologram pressure typically remains finite at the edge of the measurement aperture. Patch near-field acoustical holography (NAH) has been developed specifically to mitigate the effects related to that windowing.
J Stuart Bolton
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ACOUSTO-OPTIC SENSING FOR NEAR-FIELD ACOUSTIC HOLOGRAPHY
Inter-Noise 2022, 2023Near-field acoustic holography (NAH) is a very powerful and widely used technique for the study of complex acoustic radiators. NAH enables to quickly understand how a complex source radiates into the medium. The technique is particularly suitable at low frequencies.
SA VERBURG +2 more
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Surface decomposition method for near-field acoustic holography
The Journal of the Acoustical Society of America, 2012Near-field acoustic holography reconstruction of the acoustic field at the surface of an arbitrarily shaped radiating structure from pressure measurements at a nearby conformal surface is obtained from the solution of a boundary integral equation. This integral equation is discretized using the equivalent source method and transformed into a matrix ...
Nicolas P, Valdivia +3 more
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Measurement of confined acoustic sources using near-field acoustic holography
The Journal of the Acoustical Society of America, 2009Due to excessive reverberation or to the presence of secondary noise sources, characterization of sound sources in enclosed space is rather difficult to perform. In this paper a process layer is used to recover the pressure field that the studied source would have radiated in free space.
Langrenne, Christophe +2 more
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Research on Patch Near-Field Acoustic Holography
Applied Mechanics and Materials, 2011Support vector regression is used to establish a kind of patch near-field acoustic holography. The regression functions are constructed by treating the measured data on the patch holography as training samples, and then the data outside the measurement aperture are extrapolated. The experimental results show that the extrapolation of the sound pressure
Hai Chao Zhu +3 more
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Hybrid near-field acoustic holography
The Journal of the Acoustical Society of America, 2003Hybrid near-field acoustical holography (NAH) is developed for reconstructing acoustic radiation from an arbitrary object in a cost-effective manner. This hybrid NAH is derived from a modified Helmholtz equation least squares (HELS) formula that expands the acoustic pressure in terms of outgoing and incoming waves.
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