The auditory system involves sound collection (auricle), transmission (external auditory canal, tympanic membrane, ossicular chain), transduction (cochlear hair cells in the organ of Corti), and neural processing (spiral ganglion neurons, CN VIII, brainstem auditory nuclei, auditory cortex). Conductive hearing loss (CHL) results from any impediment in the external or middle ear preventing efficient sound energy transfer to the cochlea. Common causes include cerumen impaction, foreign bodies, otitis media with effusion, TM perforation, otosclerosis (fixation of stapes footplate), and cholesteatoma. Sensorineural hearing loss (SNHL) results from damage to cochlear hair cells (sensory) or the auditory nerve (neural). Presbycusis involves progressive loss of outer hair cells starting at the cochlear base (high-frequency loss). Noise-induced hearing loss involves mechanical destruction and metabolic exhaustion of hair cells, particularly at 4000 Hz. Ototoxic drugs (aminoglycosides inhibit mitochondrial protein synthesis in hair cells; cisplatin generates reactive oxygen species; loop diuretics alter endolymphatic potassium homeostasis). Mixed hearing loss involves both conductive and sensorineural components. The nurse performs comprehensive auditory assessment, interprets tuning fork tests, manages ototoxicity monitoring protocols, coordinates audiology referrals, and provides patient education on hearing...