I. Non-genetic factors 1. Pregnancy Viral infections of the fetus, such as influenza, rubella, cytomegalovirus, syphilis spirochete infection; pregnancy complications, such as diabetes, nephritis, sepsis; use of large amounts of ototoxic drugs. 2. Perinatal and neonatal period Premature birth, very low weight babies, birth asphyxia and hypoxia, neonatal ischemic-hypoxic encephalopathy, obstructed labor, jaundice caused by neonatal blood group incompatibility. 3. Various acute and chronic diseases, ototoxic drugs, chronic diseases of systemic and other systems and organs (low A, chronic glomerulonephritis, nephrotic syndrome, SLE, hypertension, etc.) 4. Others Head trauma, noise exposure, blast, senile hypoacusis. II, hereditary factors can exist autosomal dominant, recessive, X-linked recessive, dominant and mitochondrial inheritance (matrilineal inheritance) mode of inheritance. The most common mode of inheritance is autosomal recessive inheritance, in which the parents of the patient are normal hearing people, but carry the disease-causing gene and pass it on to their offspring, who have affected hearing.