Alveolar breath sounds are the sounds of breathing in the lungs that can be heard through a stethoscope. It generally refers to the sound produced when air enters the lungs and moves in and out of the trachea, bronchi, bronchioles and alveoli during respiratory movements. Different alveolar breath sounds have different clinical significance, both physiological and pathological. Generally, decreased alveolar breath sounds can be seen in restrictive ventilation disorders, such as pneumothorax, atelectasis, pulmonary fibrosis and so on. Enhanced alveolar breath sounds can be seen in increased exercise, excitement, mental stress, or due to a persistent state of hyperthermia, hyperthyroidism, respiratory distress syndrome caused by various reasons, persistent asthma and so on. In addition, the alveolar breath sounds become rougher, mainly seen in the inflammatory reaction of the lungs.