  Helioseismology is the study of the variations in the internal structure and
properties of the dynamics of the Sun from measurements of its surface
oscillations. With the 2010 launch of the Solar Dynamics Observatory (SDO) we
are undoubtedly approaching a new dawn for local helioseismology, as the extent
and quality of raw surface oscillation data has never been better. However,
advances in theory and modelling are still required to fully utilise these
data, especially in magnetic active regions and sunspots, where the physics is
poorly understood.
