  We review a semiclassical theory of high-field noise in degenerate
conductors, based on propagator solutions to the Boltzmann equation for the
fluctuation distribution function. The theory provides a microscopic
description of correlation-induced suppression of noise in quantum-confined
systems, such as heterojunction devices. It is also capable of describing
diffusive conductors in the mesoscopic regime. We discuss nonequilibrium
thermal noise in a simple model of a mesoscopic wire.
