Research on acoustical holography. The basic theory of acoustical holography using a hemispherical hologram.
نویسندگان
چکیده
منابع مشابه
Fast wideband acoustical holography.
Patch near-field acoustical holography methods like statistically optimized near-field acoustical holography and equivalent source method are limited to relatively low frequencies, where the average array-element spacing is less than half of the acoustic wavelength, while beamforming provides useful resolution only at medium-to-high frequencies. With adequate array design, both methods can be u...
متن کاملWideband acoustical holography
Patch Near-field Acoustical Holography (NAH) methods like SONAH and ESM are limited to relatively low frequencies where the average array inter-element spacing is less than half a wavelength, while beamforming provides useful resolution only at medium-to-high frequencies. With adequate array design, both methods can be used with the same array. But for holography to provide good low-frequency r...
متن کاملAdvances in Computer Reconstruction of Acoustical Holography
The article describes the results of two methods: the Fresnel approximation and the convolution method used for the exact Rayleigh-Sommerfeld equation. Curves for the Fresnel approximation are shown as a function of flaw depth and number of sample points. Despite a violation of the fresnel condition, an image can be achieved without visible phase distortion. This and its limits are shown on syn...
متن کاملMultisource statistically optimized near-field acoustical holography.
This 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 functions in contrast to an EWM restricted to a ...
متن کاملTime Domain Acoustical Holography and Its Applications
SOUND AND VIBRATION/FEBRUARY 2001 This article describes Time Domain Acoustical Holography, its implementation in Brüel & Kjær’s Non-Stationary Spatial Transformation of Sound Fields (NS-STSF) system and its application to solve a few noise source location problems in the automotive industry. Essentially, Time Domain Holography provides spatial mapping of a radiated sound field with a time reso...
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ژورنال
عنوان ژورنال: TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series C
سال: 1985
ISSN: 0387-5024,1884-8354
DOI: 10.1299/kikaic.51.1991