  Heavy ion collisions at RHIC/LHC energies are well described by the (nearly
ideal) hydrodynamics. Last year this success has been extended to higher
angular harmonics, $v_n,n=3..9$ induced by initial-state perturbations, in
analogy to cosmic microwave background fluctuations. Here we use hydrodynamics
to study sound propagation emitted by quenched jets.
  We use the so called "geometric acoustics" to follow the sound propagation,
on top of the expanding fireball. The conical waves, known as "Mach cones",
turn out to be strongly distorted. We show that large radial flow makes the
observed particle spectra to be determined mostlly by the vicinity of their
intersection with the fireball's space-like and time-like freezeout surfaces.
We further show how the waves modify the freezeout surfaces and spectra. We end
up comparing our calculations to the two-particle correlation functions at
RHIC, while emphasizing that studies of dijet events observed at LHC should
provide much better test of our theory.
