Pathophysiology
Clinical meaning
Hearing depends on sound wave transmission through the external ear canal to the tympanic membrane, amplification by the ossicular chain (malleus, incus, stapes) in the middle ear, and transduction by hair cells of the organ of Corti in the cochlea. The cochlea converts mechanical vibration into neural signals transmitted via the vestibulocochlear nerve (CN VIII) to the auditory cortex. Conductive hearing loss results from impaired sound transmission through the external or middle ear due to cerumen impaction, otitis media, tympanic membrane perforation, otosclerosis, or cholesteatoma. Sensorineural hearing loss (SNHL) results from damage to the cochlear hair cells or auditory nerve from noise exposure, aging (presbycusis), ototoxic medications, Meniere disease, or congenital causes. The nurse assists with hearing assessments as directed, communicates effectively with hearing-impaired patients, administers medications as ordered, and reports changes in auditory function to the nursing team.