  Hydrodynamic description of a fireball produced in high energy heavy ion
collisions has been recently supplemented by a very successful study of
acoustic perturbation created by the initial state perturbations. We discuss
sound produced at later stages of the collision, as the temperature drops below
critical, $T<T_c$, and originated from the Rayleigh-type collapse of the QGP
clusters. In certain analytic approximation we study distorted "sound spheres"
and calculate modifications of the particle spectra and two-particle
correlators induced by them. Unlike for initial state perturbations studied
previously, we propose to look for those late-time sounds using rapidity
correlations, rather than the azimuthal angles of the particles. We then
summarize known data on rapidity correlations from RHIC and LHC, suggesting
that the widening of those can be the first signature of the late-time sounds.
