Hearing Loss is the result of damage to which structures in the ear?

• A. Hair cells and accompanying nerve fibers in the ear
• B. The eardrum only
• C. Cochlear bones only
• D. Outer ear canal

Answer: (A)

Sound is heard when vibrations reach the inner ear and are converted into electrical signals by hair cells on the basilar membrane; those signals are then carried to the brain by the auditory nerve fibers. If the hair cells themselves are damaged, or the connected nerve fibers are damaged, this transduction or transmission of the signal is disrupted, leading to hearing loss. The eardrum, middle-ear bones, or outer ear canal mainly affect how much sound energy actually reaches the inner ear (conductive pathways); damage there tends to cause conductive hearing loss, not a direct failure of the neural signal. Therefore, damage to the hair cells and their accompanying nerve fibers is the most direct cause of hearing loss, making that option the best answer.