  Time-distance helioseismic measurements in surface- and deep-focus geometries
for wave-paths that distinguish surface magnetic contributions from those due
to deeper perturbations beneath a large sunspot are presented and analysed.
Travel times showing an increased wave speed region extending down to about 18
Mm beneath the spot are detected in deep-focus geometry that largely avoids use
of wave field within the spot. Direction (in- or out-going wave) and surface
magnetic field (or focus depth) dependent changes in frequency dependence of
travel times are shown and identified to be signatures of wave absorption and
conversion in near surface layers rather than that of shallowness of sunspot
induced perturbations.
