  We observe and characterize the scattering of acoustic wave packets by a
sunspot, in a regime where the wavelength is comparable to the size of the
sunspot. Spatial maps of wave traveltimes and amplitudes are measured from the
cross-covariance function of the random wave field. The averaging procedure is
such that incoming wave packets are plane wave packets. Observations show that
the magnitude of the traveltime perturbation caused by the sunspot diminishes
as waves propagate away from the sunspot -- a finite-wavelength phenomenon
known as wavefront healing. Observations also show a reduction of the amplitude
of the waves after their passage through the sunspot. A significant fraction of
this amplitude reduction is due to the defocusing of wave energy by the fast
wave-speed perturbation introduced by the sunspot. This ``geometrical
attenuation'' will contribute to the wave amplitude reduction in addition to
the physical absorption of waves. In addition, we observe an enhancement of
wave amplitude away from the central path: diffracted rays intersect with
unperturbed rays (caustics) and wavefronts fold and triplicate. Thus we find
that ray tracing is useful to interpret these phenomena, although it cannot
explain wavefront healing.
