The effective coefficients in the problem of the acoustic wave propagation have been calculated for a multiscale 3D medium by using a subgrid modeling approach. The density and the elastic stiffness have been represented by the Kolmogorov multiplicative cascades with a log-normal probability distribution. The wavelength is assumed to be large as compared with the scale of heterogeneities of the medium. We consider the regime in which the waves propagate over a distance of the typical wavelength in source. If a medium is assumed to satisfy the improved Kolmogorov similarity hypothesis, the term for the effective coefficient of the elastic stiffness coincides with the Landau-Lifshitz-Matheron formula. The theoretical results are compared with the results of a direct 3D numerical simulation.