III. Sudden deafness, tinnitus and vertigo. 1. Sudden deafness: Hyperbaric oxygen therapy can improve blood circulation in the inner ear, improve the state of hypoxia, increase aerobic metabolism, accelerate the repair of inner ear nerves, and help improve hearing and tinnitus symptoms. The Chinese Society of Otolaryngology, Head and Neck Surgery has adopted hyperbaric oxygen as one of the main treatment methods for sudden deafness, and clinical studies have shown that the earlier the hyperbaric oxygen treatment, the higher the improvement rate. Our department treats hundreds of patients with sudden deafness every year, and the total efficiency of hyperbaric oxygen treatment can reach more than 80％ with the comprehensive treatment of drugs. 2. Tinnitus: It is a subjective sensation without an external corresponding sound source, and its incidence is extremely high, and it is a symptom accompanying many diseases. However, there is no specific treatment for tinnitus. It has been reported that the cure rate of tinnitus treated with hyperbaric oxygen combined with medication can reach 70％. 3. Vertigo: Vertigo is a distorted reflection of the spatial relationship between human and the surrounding environment in the cerebral cortex. Hyperbaric oxygen therapy for this disease can not only increase the blood oxygen content, increase the oxygen diffusion distance, correct the inner ear ischemia; relieve the insufficient blood supply of vertebral and basilar arteries; hyperbaric oxygen also reduces the excitability of sympathetic nerve, which can release the local small blood vessel spasm. It has been reported that the efficiency of hyperbaric oxygen treatment for vertigo reaches 80％ or more.