  We analyze the spectral properties of a very general two-channel
fermion-boson transport model in the insulating and metallic regimes, and the
signatures of the metal-insulator quantum phase transition in between. To this
end we determine the single particle spectral function related to
angle-resolved photoemission spectroscopy, the momentum distribution function,
the Drude weight and the optical response by means of a dynamical (pseudo-site)
density-matrix renormalization group technique for the one-dimensional
half-filled band case. We show how the interplay of correlations and
fluctuations in the background medium controls the charge dynamics of the
system, which is a fundamental problem in a great variety of advanced
materials.
