Results 171 to 180 of about 1,666 (211)
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Subwavelength acoustic metamaterial with tunable acoustic absorption
The Journal of the Acoustical Society of America, 2015We present numerical simulations and experimental measurements for ultrasonic transmission through a subwavelength metamaterial consisting of an array of hollow cylinders embedded in a soft elastic matrix. The mechanical properties of the matrix, the lattice constant, and the size of the cylinders are optimized in order to maximize sound absorption in ...
Nicolas Viard +3 more
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Acoustical Absorption of Porous Pavement
Transportation Research Record: Journal of the Transportation Research Board, 2008Acoustical absorption coefficients of more than 140 pavement cores were obtained by the impedance tube method with two microphones and cross-spectral analyses. The effectiveness of the impedance tube in predicting noise reduction for different mixes was evaluated by comparing the correlations between onboard sound intensity levels and absorption ...
James T. Nelson +3 more
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Scattering and Absorption by an Acoustic Strip
The Journal of the Acoustical Society of America, 1951A method for treating the scattering and absorption of sound in the presence of non-uniform boundary conditions is applied to the case of an infinite strip of material (of given width) placed on an infinite, otherwise hard, wall. The strip is assumed to be characterized by a normal acoustic impedance that may possess a resistive component.
Alfred Levitas, Melvin Lax
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Acoustic Impedance and Sound Absorption
The Journal of the Acoustical Society of America, 1940Theoretical curves for acoustic impedance vs. frequency, obtained by solving the equation for wave motion within the material, are compared with recently measured values of the impedance of various sound absorbing materials. The satisfactory agreement in most cases measured indicates that that for homogeneous materials the effective values of flow ...
Philip M. Morse +2 more
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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 ...
Daniel G. Cole, William R. Saunders
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Acoustics- The definitive study of acoustic absorption measurement [PDF]
The Team’s approach into the Definitive Study of Acoustic Absorption Measurement involved three methods; the Acoustic Impedance Tube, the Large Reverberation Room and the Small Reverberation Chamber. The particular interest and primary focus of this study is to obtain the sound absorption coefficient, α of the various acoustic materials that were ...
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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 in Sand and Soil
The Journal of the Acoustical Society of America, 1948The acoustic absorption properties of sand and soil with varying amounts of water, ranging from dry to saturated, have been investigated. In most of the work the frequency range was 10–30 kc, although data were obtained at as high as 150 kc. Two methods were used.
W. L. Nyborg, I. Rudnick
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Mechanism of Acoustic Absorption in Tissue
The Journal of the Acoustical Society of America, 1952A viscous mechanism for the absorption of ultrasonic energy in tissue is considered. It is shown that the viscous forces acting between a suitably chosen distribution of suspended particles or structure elements and a suspending liquid can account for the experimentally observed linear relations between acoustic absorption coefficient and ultrasonic ...
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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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