The purpose of lung auscultation is to determine the location and nature of disease and the type of disease. The six areas of chest auscultation refer to the hilum, apex and base of the lungs bilaterally, located at the second intercostal space in the midclavicular line, the fourth intercostal space next to the sternum and the sixth intercostal space in the midaxillary line, respectively. The order of auscultation is from the apex of the lungs from top to bottom, and the anterior chest, lateral chest and back are auscultated respectively. However, there are no strict clinical rules for the lung auscultation sites, and the physician may add additional sites as appropriate to the patient’s condition. During auscultation, the patient needs to breathe according to the doctor’s instructions, and each auscultation site is usually listened to for 1-2 respiratory cycles. At the same time, each person’s breath sounds are different, and their strength and size are related to gender, age, the depth of breathing, and the thickness of the chest wall. Generally men have stronger alveolar breath sounds than women, and children have stronger alveolar breath sounds than older people. In pathological states, abnormal breath sounds and rales can be heard, and the rales include dry and wet rales. Diminished or absent breath sounds, prolonged breath sounds, intermittent breath sounds, and coarse breath sounds are all abnormal breath sounds. Abnormal breath sounds often indicate possible diseases: 1. diminished or absent breath sounds: if a tumor occurs in the above-mentioned area, or if a foreign body compresses the trachea causing tracheal stenosis, obstructive emphysema, massive pleural effusion, or pneumothorax, diminished or absent breath sounds can be heard; 2. prolonged breath sounds: if a patient suffers from chronic bronchitis, bronchial asthma, etc., a relative prolongation of expiration as well as dry and wet rales can be heard. 3, other: if there is a large cavity formed by the solid stage of lobar pneumonia, lung abscess, cavernous tuberculosis, or a moderate amount of pleural effusion compressing the lung tissue and forming compressive atelectasis, abnormal bronchial breath sounds as well as wet rales can be heard in the region.