  We present observational evidence for the presence of MHD waves in the solar
photosphere deduced from SOHO/MDI Dopplergram velocity observations. The
magneto-acoustic perturbations are observed as acoustic power enhancement in
the sunspot umbra at high-frequency bands in the velocity component
perpendicular to the magnetic field. We use numerical modelling of wave
propagation through localised non-uniform magnetic field concentration along
with the same filtering procedure as applied to the observations to identify
the observed waves. Guided by the results of the numerical simulations we
classify the observed oscillations as magneto-acoustic waves excited by the
trapped sub-photospheric acoustic waves. We consider the potential application
of the presented method as a diagnostic tool for magnetohelioseismology.
