Rales are additional sounds other than respiratory sounds, due to tracheobronchial Putian Tongqing for or lumen partial obstruction and other lesions; according to the nature of the sound, can be divided into dry rales and wet rales, dry rales are generally divided into snoring sounds and whistling sounds; wet rales have coarse, medium and fine sounds, twisted pronunciation and fine wet rales are very similar in nature, sometimes more difficult to identify. Differentiation between wet rales and pleural friction sounds: In dry pleurisy, the surface is rough, and the sound emitted by the wall layer and the dirty layer of pleura rubbing against each other during breathing is pleural friction sound, which is easily confused with wet rales during auscultation, pleural friction sounds can be heard during expiration and inspiration, and the sound is often clearer when deep breathing or pressurization disappears when breath is held, and pleural friction is felt on palpation, and coughing cannot change other properties often accompanied by chest pain, while wet rales The cough can not change other properties and is often accompanied by chest pain, while wet rales are more frequent during inspiration, or clearer at the end of inspiration coughing can sometimes disappear. When there is a subcutaneous emphysema in the chest, a sound similar to twisting hair can be heard on auscultation, which is similar to wet rales, but this sound can be heard during both expiration and inspiration, and the gas can also be displaced in the subcutaneous tissue when pressed with the hand to form a sound, just like twisting hair or gripping snow.