  We present a dynamic model based on the linear sigma model with constituent
quarks that allows for studying the explicit propagation of fluctuations at a
chiral critical point and a first-order phase transition. The coupled dynamics
of the sigma field and the quarks is derived selfconsistently. Hereby, the
sigma field evolves according to a semiclassical Langevin equation of motion,
while the evolution of the quarks is described fluid dynamically in order to
model the expansion of a hot fireball in heavy-ion collisions. Dissipative
processes and fluctuations in the Langevin equation are allowed under the
assumption of energy-momentum conservation of the coupled system. We study the
evolution of the constituent quark masses in this nonequilibrium set up.
