VELOCITY SHIFT USING THE RYTOV APPROXIMATION

The high-frequency propagation of acoustic plane waves in a weakly het erogeneous random stsationary 2-D medium is considered. The apparent v elocity of the wave is larger than the velocity corresponding to the b ackground homogeneous medium; the difference is called velocity shift. Both this shift and the variance of the apparent velocity are calcula ted using the Rytov approximation; explicit formulas are given when th e covariance of the medium is Gaussian. This enables one to show sever al properties of the shift and the variance, which art: illustrated by some numerical experiments on the wave equation. (C) 1998 Acoustical Society of America. [S0001-4966(98)04210-6].