Wet rales are one of the important signs during auscultation of the lungs. The mechanism of formation is due to the presence of secretions (such as sputum, exudate, blood, mucus, pus, etc.) in the whistle tract as the gas passes through it, which can form blisters that are produced when the blisters rupture. It is divided into coarse, medium and fine wet rales and twisted sounds. The distribution may be limited or both lung fields may be full of wet rales. It is often seen in bronchitis, pneumonia, bronchiectasis, pulmonary stasis, pulmonary edema, pulmonary infarction, etc. As a result of inspiration, gas through the inspiratory tract of secretions such as exudate, sputum, blood mucus and pus, the formation of blisters, rupture generated by the sound, or due to the small bronchial wall due to secretion adhesion and trapped closed, when inspiration, the sudden opening of re-inflation produced by the burst sound. Features: wet rales for the additional sound of the whistling sound, intermittent and brief, often more than once in a row, in the whistling or inspiration at the end of the obvious, sometimes also appear in the early part of the whistling more constant, the nature is not easy to change, in, small blister sound can be present at the same time, coughing can be reduced or disappear. Classification: 1, coarse wet rales: occur in the trachea, the main bronchus or cavity site, more appear in the early inspiration. 2, medium wet rales: occurring in the medium bronchi, mostly appearing in the late inspiratory period. 3.Fine wet rales: occurring in small bronchi, mostly appearing in the late inspiratory period. 4.Twisted sounds: very fine and uniform wet rales, mostly heard at the end of inspiration. Clinical significance: wet rales are the manifestation of lung and bronchial lesions. The scattered distribution of wet rales is common in bronchitis, bronchopneumonia, hematogenous tuberculosis and pulmonary edema; the distribution at the base of both lungs is common in pulmonary stasis, pulmonary edema and bronchopneumonia; the one-sided or restricted distribution is common in pneumonia, tuberculosis, bronchiectasis, pulmonary abscess, lung cancer and pulmonary hemorrhage. Croup is also called dry rales (wheezes,rhonchi). All bronchial asthma attacks are bound to have rales. In this case, in addition to the extensive fine bronchospasm, the intensity of the rales is greater if they are accompanied by swelling of the fine bronchial mucosa and retention of secretions in the lumen. Clinically, extensive and pronounced croup is one of the most important signs in the diagnosis of bronchial asthma and wheezing chronic bronchitis. The presence of croup is mainly due to extensive fine bronchospasm in the lungs, a pathological whistling sound produced by airflow through the narrow fine bronchial lumen during the whistle, and is most pronounced during the whistle. Croup is characterized by a high pitch, a musical sound like a wire tremor, a long duration and a pronounced whistling sound that basically disappears during inspiration. This pathological whistling sound can also occur in cases of obstructed ventilation caused by other diseases. In the case of bronchial foreign bodies and endobronchial tuberculosis, croup is often detected during auscultation. However, this croup is usually confined to one side of the lung or to one part of the lung where the obstruction exists, and is rarely widespread on both sides. Croup can also be present during cardiogenic asthma attacks, but it is present during both inspiration and whistling, and the prolongation of the whistling time is much less pronounced than in bronchial asthma.