They may be fine, medium, or course.-crackles result from air moving through airways that contain fluid. heard during inspiration and expiration, crackles are discrete sounds that vary in pitch and intensity. theyre classified as fine, medium, or coarse. pleural friction rubs have a distinctive grating sound. as the name indicates, these breath sounds result when inflamed pleurae rub together. continuous, highpitched, musical squeaks, called wheezes, result when air moves rapidly through airways narrowed by asthma or infection or when an airway is partially obstructed by a tumor or foreign body. wheezes, like gurgles, occur on expiration and sometimes on inspiration. loud, coarse, low-pitched sounds resembling snoring are called gurgles. these sounds develop when thick secretions partially obstruct airflow through the large upper airways.