What separates the outer ear from the middle ear and helps transmit sound from the air to the ossicles?

• A. Auditory Canal
• B. Tympanic Membrane
• C. Pinna
• D. Vestibule

Answer: (B)

The boundary between the outer ear and middle ear is the tympanic membrane, the eardrum. It sits at the end of the external auditory canal and vibrates in response to airborne sound waves. Those vibrations are then passed to the ossicular chain—the malleus, incus, and stapes—which amplify and transfer the energy into the inner ear. This membrane both separates the outer and middle ear and converts acoustic energy into mechanical energy that the middle ear can deliver to the inner ear. The auditory canal simply carries sound to the eardrum, the pinna gathers sounds from the environment, and the vestibule is part of the inner ear involved in balance rather than hearing.