Question

a structure inside the cochlea that is covered with hair cells is called the
eardrum.
middle ear.
oval window.
basilar membrane.

Explanation:

The basilar membrane is located inside the cochlea and is lined with hair - cells which are important for auditory signal transduction. The eardrum is a separate structure that vibrates in response to sound waves. The middle ear is a part of the ear containing the ossicles. The oval window is the boundary between the middle ear and the cochlea.

Answer:

basilar membrane.