On the acoustic response of a deeply corrugated periodic surface—a hybrid t-matrix approach

The extended boundary condition (EBC) method, as proposed by Waterman [J. Acoust. Soc. Am. 57, 791-802 (1975)], is hybridized with the point-matching technique in order to derive a T matrix for a periodically corrugated surface on which either the Dirichlet or the Neumann boundary condition is imposed. The limitations imposed by the Rayleigh hypothesis on Waterman’s T matrix are overcome by a correct choice of eigenfunctions for the surface field representation. Highly corrugated surfaces can now be considered. The numerical results are compared with the data computed by Holford [J. Acoust. Soc. Am. 70, 1116-1128 (1981)], using an integral equation method, as well as with the experimental results collected by Lacasce and Tamarkin [J. Appl. Phys. 27, 138–148 (1956)].