The bronchoalveolar breath sounds are a mixture of bronchial breath sounds and alveolar breath sounds. The nature of inspiratory sounds is similar to normal alveolar breath sounds, but the pitch 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 short gap between inspiration and expiration. What are the diagnostic tests for bronchoalveolar sounds? 1, solid lung tissue: so that the bronchial breath sounds through the denser part of the solid lung; transmission to the body surface and easy to hear. The location, range and intensity of bronchial breath sounds are related to the location, size and depth of the lesion. The larger and more superficial the lesion, the stronger the sound, and vice versa. It is common in the solid phase of lobar pneumonia, where the bronchial breath sounds are strong, high-pitched, and near the ear. 2, large intrapulmonary cavity: when the large intrapulmonary cavity is connected with the bronchus and its surrounding lung tissue has solid changes present, the sound resonates in the cavity and is well conducted through the solid tissue, so clear bronchial breath sounds can be heard, commonly in patients with pulmonary abscess or cavitary pulmonary tuberculosis. 3, compressive pulmonary atelectasis: when the pleural fluid accumulates, the lung is compressed and compressive pulmonary atelectasis occurs, because the lung tissue is denser, which is conducive to the conduction of bronchial sounds, so bronchial breath sounds can sometimes be heard above the area of fluid accumulation, but the intensity is weak and distant. Abnormal bronchoalveolar breath sounds are bronchoalveolar breath sounds that are heard in the area of normal alveolar breath sounds. The mechanism for this is the presence of a small area of solid lung tissue mixed with normal air-containing lung tissue, or a deeper area of solid lung tissue covered by normal lung tissue. It is commonly heard in the early stages of bronchopneumonia, tuberculosis, lobar pneumonia, or in areas of pulmonary insufficiency above a pleural effusion.