Sudden deafness: sudden onset of sensorineural deafness of unknown cause, mostly within 3 days with rapid hearing loss. The exact etiology is unknown, and it is currently thought that it may be related to viral infection, vagal edema, vascular lesions and rupture of the vagal window membrane. Some scholars in China have suggested that disorders of iron metabolism may be one of the main pathological bases for its pathogenesis. The clinical features of this disease are: (1) sudden onset of non-volatile sensorineural hearing loss, often moderate or severe; (2) unknown cause; (3) may be accompanied by tinnitus; (4) may be accompanied by vertigo, nausea, vomiting, but no recurrent attacks; (5) no symptoms of cranial nerve damage other than the eighth cranial nerve; (6) the majority of monaural onset, or bilateral simultaneous or sequential involvement, bilateral deafness is often on one side (6) The deafness in one ear is often severe. The diagnosis should be differentiated from Meniere’s disease, auditory neuroma, and functional deafness. Routine investigations should include tuning fork tests, pure tone audiometry, acoustic conductance testing, brainstem auditory evoked potentials, and otoacoustic emissions. About 2% of patients may experience spontaneous, significant or partial recovery of hearing within 2 weeks of onset. The more commonly used clinical adjuvant drugs for deafness include vasodilators, blood viscosity reducing and thrombolytic drugs, neurotrophic drugs and energy preparations, which can be used as appropriate. Hyperbaric Oxygen Therapy: The treatment of sensorineural deafness by hyperbaric oxygen alone has no definite efficacy, but it has some auxiliary therapeutic effect on early drug deafness, noise deafness, sudden deafness, traumatic deafness, etc. The combined application with drug therapy can help improve the therapeutic effect.