  The recently suggested swing interaction between fast magnetosonic and
Alfv\'en waves (2002) is generalized to inhomogeneous media. We show that the
fast magnetosonic waves propagating across an applied non-uniform magnetic
field can parametrically amplify the Alfv\'en waves propagating along the field
through the periodical variation of the Alfv\'en speed. The resonant Alfv\'en
waves have half the frequency and the perpendicular velocity polarization of
the fast waves. The wavelengths of the resonant waves have different values
across the magnetic field, due to the inhomogeneity in the Alfv\'en speed.
Therefore, if the medium is bounded along the magnetic field, then the
harmonics of the Alfv\'en waves, which satisfy the condition for onset of a
standing pattern, have stronger growth rates. In these regions the fast
magnetosonic waves can be strongly 'absorbed', their energy going in
transversal Alfv\'en waves. We refer to this phenomenon as 'Swing Absorption'.
This mechanism can be of importance in various astrophysical situations.

Astrophysics