Tympanometry measures middle ear _________ as a function of _________.

Tympanometry is a test designed to assess the function of the middle ear, specifically focusing on the mobility of the tympanic membrane (eardrum) in response to changes in air pressure within the external ear canal. In this context, the correct answer indicates that tympanometry measures middle ear mobility as a function of external ear canal pressure.

During tympanometry, a small probe is placed in the ear canal which varies the air pressure. The mobility of the tympanic membrane is evaluated by observing how well it moves in response to these pressure changes. When pressure in the ear canal is balanced with the pressure in the middle ear, maximum mobility of the tympanic membrane is observed, and this is reflected in the tympanogram.

Understanding this concept allows hearing professionals to identify potential issues like fluid in the middle ear, ear infections, or problems with the Eustachian tube. Other options would not accurately describe the relationship being assessed by tympanometry. For example, measuring pressure in relation to hearing level does not grasp the core purpose of tympanometry, which focuses on the mechanical movement of the middle ear structures rather than auditory perception directly.