  With numerical experiments we explore the feasibility of using high frequency
waves for probing the magnetic fields in the photosphere and the chromosphere
of the Sun. We track a plane-parallel, monochromatic wave that propagates
through a non-stationary, realistic atmosphere, from the convection-zone
through the photosphere into the magnetically dominated chromosphere, where it
gets refracted and reflected. We compare the wave travel time between two fixed
geometrical height levels in the atmosphere (representing the formation height
of two spectral lines) with the topography of the surface of equal magnetic and
thermal energy density (the magnetic canopy or beta=1 contour) and find good
correspondence between the two. We conclude that high frequency waves indeed
bear information on the topography of the `magnetic canopy'.
