The bronchoalveolar breath sounds are a mixture of bronchial breath sounds and alveolar breath sounds. The nature of the breath sounds is similar to that of normal alveolar breath sounds, but the pitch is higher and louder. The nature of the expiratory sounds is similar to the bronchial breath sounds, but the intensity is slightly weaker, the pitch is slightly lower, the tube-like nature is less and the expiratory phase is shorter, and there is a very short gap between inspiration and expiration. The inspiratory phase of bronchoalveolar breath sounds is approximately the same as the expiratory phase. In normal subjects, bronchoalveolar breath sounds can be heard at the level of the 1st to 2nd rib space on both sides of the sternum, the 3rd to 4th thoracic vertebrae in the interscapular region, and the anterior and posterior parts of the lung apices. The nature of the breath sounds is similar to that of normal alveolar breath sounds, but the tone is higher and louder. The nature of the expiratory sounds is similar to that of bronchial breath sounds, but the intensity is slightly weaker, the pitch is slightly lower, the tube-like nature is less and the expiratory phase is shorter, and there is a very brief gap between inspiration and expiration. Abnormal bronchoalveolar sounds often suggest the following diseases: 1, solid lung tissue, such as the solid stage of lobar pneumonia, tuberculous caseous pneumonia, pulmonary infarction, lung cancer, etc. 2, lung tissue compression, such as pleural effusion or tumor. 3, there are large cavities in the lungs resonating with the bronchi. Cultivate good hygiene habits, the room should be ventilated frequently to keep the air fresh. Attention should be paid to the combination of work and rest, to have enough nutrition and sleep, but also appropriate outdoor activities and physical exercise, which can enhance physical fitness and improve resistance.