Hearing loss (epicophosis): Hearing loss can be classified into three types based on the location of the lesion: ① Sensorineural hearing loss: Caused by lesions in the inner ear and cochlear nerve, seen in labyrinthitis, acoustic neuroma, etc. Hearing impairment is mainly at high frequencies, often accompanied by vertigo. Rinne test shows air conduction greater than bone conduction, Weber test sound deviates to the healthy side. ② Conductive hearing loss: Caused by lesions in the middle ear or (and) outer ear, such as acute and chronic otitis media or otosclerosis. Hearing loss is mainly at low frequencies, not accompanied by vertigo. Rinne test shows bone conduction greater than air conduction, Weber test sound deviates to the affected side. ③ Central hearing loss: Rare, caused by bilateral cochlear nuclei and supranuclear auditory central pathway lesions leading to hearing loss, often accompanied by other symptoms and signs of brainstem or cerebral lesions. Sensorineural hearing loss should be distinguished from conductive hearing loss caused by ear diseases as shown in the table.