Anisotropic spectra of acoustic type turbulence
  We consider the problem of spectra for acoustic type of turbulence generated by shocks being randomly distributed in space. We show that for turbulence with a weak anisotropy such spectra have the same dependence in $k$-space as the Kadomtsev-Petviashvili (KP) spectrum: $E(k)\sim k^{-2}$. However, the frequency spectrum has always the falling $\sim \omega^{-2}$, independently on anisotropy. In the strong anisotropic case the energy distribution relative to wave vectors takes anisotropic dependence forming in the large $% k $ region the spectra of the jet type. 
E. Kuznetsov and V. Krasnoselskikh