The nasal sound keeps appearing after the recovery from the cold mainly because of the upper respiratory tract infection, the inflammation has been controlled but the inflammatory reaction of congestion, edema and exudation of inflammatory substances from the nasal mucosa has not completely subsided, and the damaged nasal mucosa caused by inflammation still has the process of self-repair. The inflammatory material secreted on the mucosa of the nasal cavity contains a large amount of shed tissue fragments, dead immune cells and pathogens, and the inflammatory secretions still obstruct the nasal cavity to varying degrees, and the nasal cavity is still narrow compared to normal. When breathing movements or when the patient speaks and pronounces words, the airflow vibrates through the nasal cavity and a nasal sound occurs. It is more commonly seen clinically in the remission phase of acute rhinitis and chronic rhinitis.