Ear & Hearing
Tympanometry is an objective measurement that assesses the pressure state in the middle ear (which lies behind the eardrum).
In a normal ear, the air pressure in the middle ear (i.e the inner side of the eardrum) and that of the outer ear (which is the same as the pressure of the air around us) are equal. The Eustachian tube, which connects the middle ear to the nasopharynx (the part of the throat at the back of the nose) allows for this equalisation of air pressure. When the Eustachian tube is blocked or does not function well, there is insufficient air entering the middle ear and this creates a negative pressure (vacuum); if this situation persists, the middle ear may become filled with fluid (middle ear effusion).
Tympanometry is performed with a probe inserted into the ear canal. The probe emits a pure tone and measures the amount of sound that passes through the eardrum at different pressure levels.
The graphical patterns shown on a tympanogram can demonstrate a negative pressure state (type C) or middle ear effusion (type B). A normal (type A) tympanogram would rule out either of these states