Efficiency of single noise barriers

Hothersall, David; Chandler-Wilde, Simon N.; Hajmirzae, M.N.

doi:10.1016/0022-460x(91)90765-c

Cited by 128 publications

(92 citation statements)

References 17 publications

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“…In the numerical simulations, dimension of elements was taken to be less than λ/5 to give a reasonable representation of constant surface pressure over an element [6]. The QRD is represented by a box with the top surface having an admittance distribution as given by the simple phase changes due to plane wave propagation within the QRD wells.…”

Section: Numerical Modelling Methodsmentioning

confidence: 99%

Performance of profiled single noise barriers covered with quadratic residue diffusers

Monazzam

Lam

2005

Applied Acoustics

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Section: Numerical Modelling Methodsmentioning

confidence: 99%

Performance of profiled single noise barriers covered with quadratic residue diffusers

Monazzam

Lam

2005

Applied Acoustics

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“…(1), (5) and (10), respectively. Since the insertion loss of the barrier in such threedimensional geometry agrees approximately with that in a two-dimensional field with the same cross-sectional geometry [12], the two-dimensional insertion losses are provided by numerical analyses with 2D-BEM. The accuracy of the four-path model is examined by comparison with the numerical results.…”

Section: Verification Of the Propagation Prediction Modelmentioning

confidence: 98%

Simple prediction method for sound propagation behind edge-modified barriers

Okubo

Yamamoto

2007

Acoust. Sci. & Tech.

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In this paper, we describe a method for predicting sound propagation behind barriers with an acoustical device mounted on their top edge to reduce the diffracted sound. The sound-reduction efficiency of the edge-modified noise barrier was investigated previously with a sound source and a receiver located along a circular arc around the barrier top. It was reported that the efficiency is determined as a function of the angles of the source and the receiver, and that it is independent of their radii. On the basis of this finding, a procedure of predicting the diffracted sound field behind an edgemodified noise barrier is proposed in this paper. The prediction of sound propagation is simply modeled by the sum of multiple paths, which idealize interference due to ground reflection, and the angle-dependent efficiency of the edge device is applied to each path. The efficiencies of absorptive and pressure-release devices are determined by scale-model experiments, and the results are substituted into the prediction model. In comparison with the two-dimensional boundary element analyses, it is shown that the proposed procedure predicts the diffracted sound field precisely, including both the interference by ground reflection and the effect of the edge device.

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“…The sound pressure magnitude , p r î h of a line source of finite length L and radius a shown in Figure 3 is defined by (2), where p r ax^h represents the magnitude proportional with /r 1 in the far field (3), and H î h is the directivity factor which depends on the sync function or the spherical Bessel function ( J 0 ) of zero order, as in (4).…”

Section: Modelling Of the Sound Sourcementioning

confidence: 99%

“…For barriers with a complex shape, where no analytical method can be used, Seznec [3] proposed the development of a program that uses numerical calculation with boundary elements (Boundary Element Method, BEM). Hothersall et al [4,5] studied a number of barriers by comparing the plain barrier with barriers that had a special circular, Y-or T-shaped element installed on the top. The Y-and T-shaped elements have proven to work very well for sound diffusion.…”

Section: Introductionmentioning

confidence: 99%