Adventitious Breath Sounds: · What It Is, Causes, Signs and Symptoms, Diagnosis, and More

Adventitious breath sounds are abnormal breath sounds heard during respiration which may suggest an underlying medical condition, like chronic obstructive pulmonary disease (COPD) or heart failure. The main adventitious lung sounds are crackles, wheezes, and rhonchi. These sounds can be described based on the sound qualities. For example, distinct acoustic events may sound like a marble dropping on the floor, whereas an inseparable noise may sound like the whirring of a fan.  Sounds may also be described by whether they are continuous or intermittent; and their pitch.    

Crackles, also known as rales, are brief, non-musical sounds that resemble the crinkling of paper or ripping of velcro. Crackles may occur in both the inspiratory and expiratory phases. Although less common, rubs are another type of breath sound that occurs in both the inspiratory and expiratory phases and are characterized by a grating sound. Rubs are often confused with crackles, however, distinguishing factors of rubs include their biphasic nature (i.e., present during both inspiration expiration), localized quality (e.g., can be heard overlying a localized area on the chest wall), and is associated with overlying localized pain on the chest wall.  
 
Wheezes are high-pitched whistling or musical sounds that occur during the expiratory phase. Stridor is a specific subtype of wheezing, which is a loud musical sound with a constant pitch that is often heard in individuals with foreign bodies in the upper airways. Finally, rhonchi are coarse, rattling, continuous low-pitched sounds that also occur during the expiratory phase.