Tympanometry primarily assesses:

• A. Cochlear hair cell function
• B. Auditory nerve conduction
• C. Middle ear mobility and tympanic membrane compliance under varying ear pressure
• D. Outer ear canal impedance

Answer: (C)

Tympanometry measures how the middle ear responds to pressure changes by tracking how the tympanic membrane moves as ear canal pressure is varied. A probe tone is emitted while the pressure is swept, and the device records the tympanic membrane’s compliance (mobility) across pressures. The peak on the tympanogram reflects normal middle-ear function when pressures are balanced; reduced mobility or an absent peak points to middle-ear problems such as fluid behind the eardrum, eustachian tube dysfunction, or a perforation. This focus on middle-ear mobility under different pressures distinguishes it from tests of inner-ear hair cell function or neural conduction, and from measurements of the outer ear canal’s impedance, which tympanometry does not primarily assess.