Which test measures tympanic membrane impedance to assess middle-ear function?

Which test measures tympanic membrane impedance to assess middle-ear function?

• A. Audiogram
• B. Otoacoustic emissions
• C. Tympanometry
• D. Auditory brainstem response

Answer: (C)

Tympanometry checks how easily the eardrum and middle-ear system move when pressure changes, i.e., it measures tympanic membrane impedance. A probe in the ear canal changes air pressure while sending a small sound and listening for how much sound is reflected back. The result, a tympanogram, shows how the middle ear responds at different pressures. When the middle ear is normal, you see a peak of compliance near zero pressure, meaning the eardrum moves best at ambient pressure. If the curve is flat, there’s likely fluid in the middle ear or a perforation. A peak shifted to negative pressure points to Eustachian tube dysfunction. This test specifically targets middle-ear mechanics, unlike an audiogram (hearing thresholds), otoacoustic emissions (cochlear outer hair cell function), or auditory brainstem response (neural pathways up to the brainstem).

Tympanometry checks how easily the eardrum and middle-ear system move when pressure changes, i.e., it measures tympanic membrane impedance. A probe in the ear canal changes air pressure while sending a small sound and listening for how much sound is reflected back. The result, a tympanogram, shows how the middle ear responds at different pressures. When the middle ear is normal, you see a peak of compliance near zero pressure, meaning the eardrum moves best at ambient pressure. If the curve is flat, there’s likely fluid in the middle ear or a perforation. A peak shifted to negative pressure points to Eustachian tube dysfunction. This test specifically targets middle-ear mechanics, unlike an audiogram (hearing thresholds), otoacoustic emissions (cochlear outer hair cell function), or auditory brainstem response (neural pathways up to the brainstem).