What is the role of the tympanic membrane?

• A. It vibrates after being struck by sound waves.
• B. It secretes endolymph.
• C. It amplifies low-frequency base sounds.
• D. It generates auditory nerve impulses directly.

Answer: (A)

Sound waves are collected by the outer ear and strike the tympanic membrane, causing it to vibrate. This converts airborne acoustic energy into mechanical energy, which drives the ossicular chain (the malleus, incus, and stapes) and transfers motion to the inner ear. In this way, the tympanic membrane acts as the first transducer in hearing, initiating the mechanical amplification and transmission of sound into the fluid of the inner ear where hair cells convert it into neural signals. The other statements don’t fit: endolymph is produced in the inner ear, not by the tympanic membrane; amplification is a result of the middle ear ossicles’ mechanics rather than a direct, selective boost by the tympanic membrane; and auditory nerve impulses are generated by hair cells in the cochlea, not by the tympanic membrane itself.