Wet rales are sounds produced by the rupture of blisters formed by gas passing through secretions such as exudate, sputum, blood, mucus and pus in the respiratory tract during inspiration, so they are also called blister sounds. Or it is thought to be the bursting sound produced by the wall of the small bronchus trapped and closed due to adhesion of secretions, which suddenly opens and re-inflates when inspiration is applied. Wet rales are one of the most important signs during auscultation of the lungs. The sound is produced by the rupture of a blister formed by gas passing through secretions (such as exudate, sputum, blood, mucus and pus) in the airways during inspiration, or by the sudden opening and re-inflation of the small bronchial walls that are trapped due to adhesion of secretions when inspiration is performed. Wet rales are additional sounds of breath sounds, intermittent and transient, often appearing more than once in succession, and are obvious at the end of inspiration or expiration; sometimes they also appear at the early stage of expiration, with a more constant location and less variable nature, and small vesicular sounds may exist at the same time, and may be reduced or disappear after coughing.