and with a wall having a two-dimensional roughness , while with sand as 

 roughness the phase shift was measured by the dye method. 



With both fi(y) and f2(y) determined equation (B-3) may now be 



written as 



1/2 



J± = [l + f"i (y) - 2fi(y) cos f2(y)l sin(iut-6) (B-5) 



u^ L J 



where 



e = tan- 1 f £l£z2 sinf 2(y) 1 



L 1 - ^(y) cos f 2 (y) J 



B-4 



