7-month-old babies make strange noises that depress the voice is an abnormal situation, may be related to phlegm in the throat, laryngeal cartilage softening, tic disorders and other factors, the specific analysis is as follows: 1. phlegm in the throat: 7-month-old babies due to age limitations, so when there is phlegm in the throat, can not be coughed up as hard as adults, but the phlegm has been retained in the baby’s throat, the baby due to discomfort, so there will be a lowered voice strange sound. 2. Laryngeal cartilage softening: the cartilage structure of the epiglottis and larynx of 7-month-old babies is underdeveloped, which may cause babies to make strange noises of lowering their voices. 3. Tourette’s syndrome: if the baby belongs to the frequent lowered voice strange sound, and also accompanied by shrugging shoulders, squeezing eyebrows and other symptoms, may be caused by tourette’s syndrome. 7 months the baby issued a low voice strange sound may have other reasons, it is recommended to timely to the hospital for relevant examinations, clear cause and actively treat the symptoms.