  Impulses efficiently propagate into nominally dry granular beds and
backscatter from buried inclusions in such beds may be potentially exploited to
image shallow buried objects (SBOs). However, reliable imaging of SBOs requires
``cleaning up'' of surface vibrations, and, in addition to 3D particle dynamics
simulations, a phenomenological model to parameterize the bed surface may be
useful for field applications. We introduce a 1D mean-field-like toy model with
two parameters that allows one to model surface vibrations, is consistent with
experiments in a granular bed, and can help estimate the approximate signal
transmission properties of the bed.
