A murmur is heard when breathing, which is most commonly caused by different degrees of inflammatory reactions in the respiratory system. Due to different degrees of congestion and edema of the airway mucosa, and even the exudation of inflammatory secretions, and even accompanied by bronchial smooth muscle contraction and spasm, resulting in narrowing of the airway, and the emergence of a variety of respiratory murmurs, such as wheezing bronchitis and bronchial asthma can be clearly heard in the lungs, irregular pulmonary rales. For the combination of obvious bacterial infection, this can be heard in the lungs with large irregular blister sounds, with coughing, coughing up sputum, respiratory murmur will be weakened or disappeared. In addition, in the case of various causes of lung infections, that is, pneumonia, you can hear fixed small and medium-sized blister sounds in the lungs at fixed foci, which will not be weakened or disappeared with coughing, and the clinical diagnosis can be clarified through auscultation combined with the CT scan of both lungs.