We study the intrinsic torsion of almost quaternion-Hermitian manifolds via
the exterior algebra. In particular, we show how it is determined by particular
three-forms formed from simple combinations of the exterior derivatives of the
local Kaehler forms. This gives a practical method to compute the intrinsic
torsion and is applied in a number of examples. In addition we find simple
characterisations of HKT and QKT geometries entirely in the exterior algebra
and compute how the intrinsic torsion changes under a twist construction.Comment: 38 page
