What is the function of the cochlea?

• A. Convert mechanical vibrations into neural signals
• B. Equalize pressure
• C. Amplify sound energy
• D. Filter stapes movement

Answer: (A)

The cochlea’s job is to convert mechanical vibrations into neural signals. When sound energy moves the tympanic membrane and ossicles, those motions create traveling waves in cochlear fluids that bend the basilar membrane. This deflection moves the hair cell stereocilia, opening mechanosensitive ion channels and letting potassium-rich endolymph depolarize the hair cells. The resulting receptor potential causes neurotransmitter release onto the auditory nerve fibers, sending neural impulses to the brain. This transduction is organized along the basilar membrane in a frequency-dependent map, with the base responding to high frequencies and the apex to low frequencies. By contrast, pressure equalization is handled by the middle ear and Eustachian tube, and amplification or filtering described here are not the cochlea’s primary transduction function.