Formation of the nonequilibrium subsystem in dynamical processes during defect generation is simulated by means of molecular dynamics. A particular process of dissipation of the low-frequency acoustic emission into high-frequency equilibrium vibrations of lattice is studied numerically. Clear heuristic reasons are used to introduce different temperatures and entropies for equilibrium and nonequilibrium subsystems. Simple relaxation equation is proposed to describe time behavior of the nonequilibrium entropy.