If a child is unable to speak, for example, at the age of 2.5 to 3 years old, or if the child does not respond to sounds, the parents should not see the doctor later than 4 years old, because for this type of child, the best age for cochlear implantation is before 4 years old, and the minimum age for implantation is 1 month. Children who have cochlear implants before the age of 4 can attend normal school or even college with good language training.