Schoch Shift Effect

The Schoch Shift Effect is a very interesting and non intuitive effect. a compression wave who travel in a liquid and strike an elastic solid close to the second critical angle, seems to split in an specular and non specular reflected lobes with the presence of a null zone (as shown bellow).

Schlieren photograph taken by Neubauer and Dragonette:

W. G. Neubauer and L. R. Dragonette, “Measurement of Rayleigh
phase velocity and estimates of shear speed by Schlieren visualization,”
J. Appl. Phys., vol. 45, no. 2, pp. 618–622, 1974.