Rales are abnormal lung sounds that can be heard when a person breathes in. They are small clicking, bubbling, or rattling sounds in the lungs and are believed to occur when air opens closed air spaces. Rales can be further described as moist, dry, fine, and coarse. Fine crackles are a type of rales that are high-pitched sounds mostly heard during inspiration. Rales can be difficult to differentiate from other abnormal lung sounds, such as rhonchi, which are gurgling or bubbling sounds. Both rales and rhonchi can be caused by infections, fluid buildup in the lungs, and chronic lung diseases like COPD. Rales are frequently associated with inflamed or infected small bronchi, bronchioles, and alveoli.