This section uses the method described in the previous → Sect. D.7 . The “unevenness” may be modelled either with a variation of the normalised absorber admittance G(x,y) or with a variation of the co-ordinates of the surface. The first method can be applied to grooves and narrow valleys, for example; the second method is applicable for slow or random variations.
If the absorber surface can be represented by a reference plane with a variable admittance \(G(x,y)\), then the admittance first is described by its Fourier series. The following example assumes in A a one-dimensional variation of the admittance \(F_{{0}}\) of the surrounding baffle wall in the form of a cosine modulation with the period length \(\ell\), and the average admittance over the absorber side length a in the x direction of a rectangular absorber with with the function \(\begin{array}[]{l@{\,}c@{\,}lr}G(x)&=&F_{0}+B\cdot\cos(2\pi x/\ell)~~~~~~~~~~~~~~~~~~~~~~~~~&(1)\\ &&&\\ &&&\\ \langle G\rangle&=&F_{0}+B\cdot...
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Mechel, F.P.: Schallabsorber. Vol. I–III, Hirzel, Stuttgart (1989, 1995, 1998)
Mechel, F.P.: Schallabsorber. Vol. I, Ch. 8: “Plane absorbers with finite lateral dimensions”, Hirzel, Stuttgart (1989)
Mechel, F.P.: Mathieu Functions; Formulas, Generation, Use. Hirzel, Stuttgart (1997)
Mechel, F.P.: A line source above a plane absorber. Acta Acustica 86, 203–215 (2000)
Mechel, F.P.: Modified mirror and corner sources with a principle of superposition. Acta Acustica 86, 759–768 (2000)
Mechel, F.P.: Schallabsorber. Vol. I, Ch. 13: Spherical waves over a flat absorber. Hirzel, Stuttgart (1989)
Ochmann, M.: The complex equivalent source method for sound propagation over an impedance plane. J. Acoust. Soc. Am. 116, 3304–3311 (2004)
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(2008). Uneven, Local Absorber Surface . In: Mechel, F.P. (eds) Formulas of Acoustics. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-76833-3_55
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