Crackles/rales are sounds that are heard when the lung field has fluid in small airways. Crackles can be heard on inspiration and expiration. Early inspiratory and expiratory crackles are heard in chronic bronchitis. Late inspiratory crackles may indicate pneumonia, CHF, or atelectasis, a complete or partial collapse of a lung or lobe of a lung. Crackles can also be considered fine (high-pitched) or course (louder and lower in pitch).