A normal 15-month-old baby should be able to say 3-5 single words other than mom and dad. If he or she still does not speak at the age of 15 months, the following possibilities should be noted: 1. Childhood autism. In addition to not being able to speak, brief eye contact with people, can not use gestures to express their needs, and can not play interactive games with children, the presence of stereotypical behavior and sensory abnormalities, etc., such as the above performance to promptly go to the hospital. 2, some genetic, metabolic or chromosomal diseases. Often accompanied by mental retardation, and accompanied by special facial features, such as small eye fissures, pass palm, etc., need to promptly go to the hospital for related checks. 3, hearing impairment. When there is a hearing impairment, the baby can not receive external signals normally, and thus will not speak, if necessary, to the Department of Five Ophthalmology for hearing diagnosis.