there is loss of continuity of the ossicles (middle ear bones) by disease or trauma
a grommet is blocked
changing pressure in the ear canal causes dizziness indicating a fistula (defect) in the bone surrounding the labyrinth (balance organ)
How?
You are not required to do anything for this test other than sit very still. The audiologist will hold a soft rubber probe at the entrance of your ear canal and you may feel a slight change of pressure in your ear.