A comparison between the Biot‐Tolstoy exact solution for wedge diffraction and a related solution that involves the Kirchhoff approximation

Biot and Tolstoy [J. Acoust. Soc. Am. 29, 381–391 (19571] have used the normal coordinate method to obtain a simple exact expression for the impulse response of a rigid wedge. This solution is appropriate to arbitrary wedge angle as well as arbitrary point receiver and explosive point source locations. Trorey [Geophysics 35, 762–784 (1970)] has developed a simple expression for the back‐scattered impulse response of a half plane in the Kirchhoff approximation. The Biot‐Tolstoy solution has been used by Medwin and Novarini [J. Acoust. Soc. Am. 67, S67(A)(1980)] to model back‐scatter from the ocean surface. In doing so, they evaluated the accuracy of a similar but earlier model [J. Acoust. Soc. Am. 64, 260–268 (1978)] that used the Trorey Helmholtz‐Kirchhoff solution. Because of the nature of the Kirchhoff approximation, the Trorey solution ignores field effects associated with shadow zones. The Biot‐Tolstoy solution, on the other hand, does not. Here, an explicit comparison between the two solutions for simplified geometries (e.g., a single half‐plane wedge) is discussed. [Work supported by NORDA.]