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Inhomogeneous absorption and geometric acoustics
The Journal of the Acoustical Society of America, 1998 The conventional formulation of geometric acoustics in the presence of inhomogeneous (spatially varying) absorption is examined. This formulation is found to fail under conditions of multipath propagation, because interference between ray paths is not taken into account when the absorptive losses are calculated.
F. D. Tappert
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Acoustic absorptivity of direct acoustic rate feedback control
The Journal of the Acoustical Society of America, 1995The fixed-gain feedback methods often provide the only means of limiting transient noise and excessive sound pressures due to unmeasurable, incoherent disturbances. The use of direct acoustic rate feedback (DARFB) to control an enclosure’s reverberant energy has the benefit over other feedback methods of larger stability margins and improved stability ...
William R. Saunders, Daniel G. Cole
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Foam acoustic absorption member
The Journal of the Acoustical Society of America, 1988A foam acoustic absorption member having a stabilizing layer with perforations and, in order to obtain a simple, stable structural shape of homogeneous resistance to flow, the stabilizing layer (2) is a wide-side wall of a hollow body (K) which wall is pressed, under thermal deformation, against the foam layer (1), the openings in said hollow body ...
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Acoustic absorption properties of materials
Construction and Building Materials, 1988Abstract The sound absorption characteristics of some 30 different but easily available sound absorbing materials have been studied previously. Presented here in brief are a selection of these materials, their description, methodology used and results obtained.
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Plate-type acoustic metamaterials for acoustic absorption.
2020International ...
Romero-García, Vicente +9 more
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Acoustical absorption by materials in a nacelle of turbojet
The Journal of the Acoustical Society of America, 2013The paper discusses the absorption of certain materials with different acoustic properties used in a nacelle of aircraft is investigated using numerical model. A model 2-D with the configuration of axisymmetrical and the differential equations of the Continuity and Helmholtz equation is realized, it couples a finite element description with a boundary ...
Ibanez R. Carlos, Panneton Raymond
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Sound Absorption Coefficients and Acoustic Impedance
The Journal of the Acoustical Society of America, 1941The relation between normal acoustic impedance and the various types of absorption coefficient has been discussed and specific formulas for the coefficients in terms of acoustic impedance have been published. Contours of constant absorption coefficient plotted as a function of the real and imaginary parts of acoustic impedance plotted on a linear scale
Richard L. Brown, Philip M. Morse
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Nonresonant acoustic absorption of Ising magnet
Theoretical and Mathematical Physics, 1994Zubarev's nonequilibrium statistical operator method is used to construct a theory of the nonresonant acoustic absorption of the linear Ising magnet, the basic Hamiltonian of which is of the two-particle kind and is treated without approximations. The frequency dependence of the absorption is determined and found to differ analytically from the well ...
I. S. Donskaya +2 more
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Experiments on Acoustic Absorption in Sand and Soil
The Journal of the Acoustical Society of America, 1950The acoustic absorption of sand and soil with varying amounts of water (dry to saturated) has been investigated the 10- to 100-kc range. Two methods were used. In one, the source and a number of equally spaced probe microphones were imbedded in the medium.
I. Rudnick +2 more
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Acoustical absorption in the atmosphere at high altitudes.
The Journal of the Acoustical Society of America, 2008Before 1978, acoustical absorption in the atmosphere was modeled semiempirically based on numerous experimental studies, especially those of Harris and Tempest. In 1969, this author presented a semiempirical model to explain the divergence of the absorption data from theoretical values predicted from classical absorption and molecular relaxation of ...
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