A tympanogram is a graphical representation of the movement of the eardrum, or tympanic membrane, in response to changes in air pressure. It is used in audiology to assess middle ear function and can help diagnose conditions such as otitis media or eustachian tube dysfunction. During the test, a small device creates variations in air pressure in the ear canal, measuring how well the eardrum moves. The results are displayed on a chart, indicating the pressure levels and compliance of the eardrum, which can provide valuable information about hearing health.