The disappearance of rumbling after coughing up sputum may be due to the fact that the airway becomes clear after the sputum is coughed up, or it may be due to a complete blockage of the airway. 1. When the airway becomes clear after coughing up sputum, there may be croup when the airway is partially blocked due to sputum. If the sputum is coughed out of the body and the airway is clear, the croup may disappear. 2. Complete airway obstruction caused by sputum. Sometimes the sputum is not completely coughed out after coughing up sputum, but the position of sputum is changed, which may lead to complete obstruction of part of the airway. This may cause local or unilateral weakening or even disappearance of lung breath sounds, and the rumbling sound also disappears. Therefore, the disappearance of rales after coughing up sputum needs to be evaluated in conjunction with specific clinical symptoms, lung auscultation and other comprehensive assessment, and individualized treatment.