A. Causes: 1. Toxic deafness caused by continuous use of antibacterial agents such as streptomycin, kanamycin, gentamicin, etc. in children after the disease; 2. Sudden deafness caused by viral infection or vascular embolism in the inner ear; 3. Infectious deafness caused by infectious diseases such as meningitis, measles, typhoid fever, etc.; 4. Explosive deafness caused by trauma or shock or noise, etc. The main symptoms are as follows: 1. hearing loss; 2. hearing loss; 3. often accompanied by tinnitus. Treatment: 1. To restore or partially restore the lost hearing; 2. To preserve and use the residual hearing as much as possible.