Pleural rubs are discontinuous or continuous, creaking or grating sounds. The sound has been described as similar to walking on fresh snow or a leather-on-leather type of sound. Coughing will not alter the sound. They are produced because two inflamed surfaces are sliding by one another, such as in pleurisy.
During auscultation, pleural rubs can usually be localized to a particular place on the chest wall. They also come and go.
Because these sounds occur whenever the patient's chest wall moves, they appear on inspiration and expiration. Pleural rubs stop when the patient holds her breath. If the rubbing sound continues while the patient holds a breath, it may be a pericardial friction rub.