  (Abridged)
  Aims: We characterize the dynamics of the quiet inter-network chromosphere by
studying the occurrence of acoustic shocks and their relation with the
concomitant photospheric structure and dynamics.
  Methods: We analyze a comprehensive data set that includes high resolution
chromospheric and photospheric spectra obtained with the IBIS imaging
spectrometer in two quiet-Sun regions. This is complemented by high-resolution
sequences of MDI magnetograms of the same targets. From the chromospheric
spectra we identify the spatio-temporal occurrence of the acoustic shocks. We
compare it with the photospheric dynamics by means of both Fourier and wavelet
analysis, and study the influence of magnetic structures.
  Results: Mid-chromospheric shocks occur as a response to underlying powerful
photospheric motions at periodicities nearing the acoustic cut-off, consistent
with 1-D hydrodynamical modeling. However, their spatial distribution within
the supergranular cells is highly dependent on the local magnetic topology,
both at the network and internetwork scale. Large portions of the internetwork
regions undergo very few shocks, as "shadowed" by the horizontal component of
the magnetic field. The latter is betrayed by the presence of chromospheric
fibrils, observed in the core of the CaII line as slanted structures with
distinct dynamical properties. The shadow mechanism appears to operate also on
the very small scales of inter-network magnetic elements, and provides for a
very pervasive influence of the magnetic field even in the quietest region
analyzed.
