  Measurements of angular correlations of hadrons with a (semi-)hard trigger
hadron in heavy-ion collisions at RHIC show large angular structures opposite
to the trigger which were a priori unexpected. These away side large angle
correlations were first observed in two-particle correlations and have recently
also been investigated in three-particle correlation measurements by the PHENIX
and STAR collaborations. We show that the correlation signal can be understood
in terms of sonic shockwaves ('Mach cones') excited by hard partons
supersonically traversing the medium. The propagation of such shocks through
the medium evolution is treated in a Monte Carlo (MC) framework. We demonstrate
that two- and especially three-particle correlations offer non-trivial insight
into the medium-averaged speed of sound and the evolution of flow. Our findings
imply that the assumption of "deflected jets" is not necessary to account for
the observed correlations.
