  We report an exact unique constant-flux power-law analytical solution of the
wave kinetic equation for the turbulent energy spectrum, $E(k)=C_1
\sqrt{\varepsilon\, a c_{\rm s} }/k$, of acoustic waves in 2D with almost
linear dispersion law, $\omega_k = c_{\rm s} k[1+(ak)^2]$, $ ak \ll 1$. Here
$\varepsilon$ is the energy flux over scales, and $C_1$ is the universal
constant which was found analytically. Our theory describes, for example,
acoustic turbulence in 2D Bose-Einstein condensates (BECs). The corresponding
3D counterpart of turbulent acoustic spectrum was found over half a century
ago, however, due to the singularity in 2D, no solution has been obtained until
now. We show the spectrum $E(k)$ is realizable in direct numerical simulations
of forced-dissipated Gross-Pitaevskii equation in the presence of strong
condensate.
