crackle, a common, abnormal respiratory sound consisting of discontinuous bubbling noises heard on auscultation of the chest during inspiration. Fine crackles have a popping sound produced by air entering distal bronchioles or alveoli that contain serous secretions, as in congestive heart failure, pneumonia, or early tuberculosis. Coarse crackles may originate in the larger bronchi or trachea and have a lower pitch. Crackles are not cleared by coughing. Compare rhonchus, wheeze. Formerly called rale. See also coarse crackle.
