Comment on "Energy Velocity of Diffusion Waves in Strongly Scattering   Media"
  A comment on the recently published article (PRL 79, 3166 (1997)) is given. The issue is if there is a unique self-consistent way in determining the effective medium in a random medium. The recently introduced effective medium theory (PRL 75, 3442 (1995)) based on the principle of energy density homogenization is also discussed. 
C.M. Soukoulis, K. Busch, M. Kafesaki, and E.N. Economou