  It was proposed that acoustic perturbations generated by the QCD phase
transition could create an inverse turbulent cascade
\cite{Kalaydzhyan:2014wca}. An assumption was that propagation toward smaller
momenta could reach the wavelength of a few km, the Universe's size at the
time. Such acoustic waves were proposed to be the source of gravity waves. The
kilometer wavelength corresponds to year-long gravity wave today, which were
recently discovered using pulsar correlations. This paper argues further that
an acoustic turbulence must be an ensemble of shocks. This brings two
consequences: First, shocks generate gravity waves much more efficiently than
sound waves due to the intermittency of matter distribution. We reconsider
gravity wave radiation, using universal emission theory for soft radiation, and
argue that soft-momenta plateau should reach wavelengths of the order of shock
mean free paths. Second, collisions of shock waves create local density excess,
which may create primordial black holes. A good tool to settle this issue can
be an evaluation of the {\em trapped surfaces} like it was done in studies of
heavy ion collisions using AdS/CFT correspondence
