Breath Sounds

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Overview & Considerations

The lung sounds are usually examined by auscultation (listening) with a stethoscope.

Normal lung sounds occur in all parts of the chest area, including above the collarbones and as low as the bottom of the rib cage. When listening to the lungs, the categories of findings include normal breath sounds, decreased or absent breath sounds, and abnormal breath sounds.

Absent or decreased sounds are inaudible (absent) or reduced in loudness (decreased) when the lungs are examined with a stethoscope. They reflect reduced airflow to a portion (segment) of the lungs, over inflation of a portion of the lungs (such as with emphysema), air or fluid around the lungs, or sometimes increased thickness of the chest wall.

There are several types of abnormal breath sounds: rales, rhonchi, and wheezes are the most common. Wheezing can sometimes be heard without a stethoscope, and other abnormal sounds are sometimes also loud enough to be detected with the unaided ear.

Rales (crackles or crepitations) are small clicking, bubbling, or rattling sounds in a portion of the lung. They are believed to occur when air opens closed alveoli (air spaces) . Rales may be further described as moist, dry, fine, coarse, among other descriptors.

Rhonchi are sounds that resemble snoring. They are produced when air movement through the large airways is obstructed or turbulent.

Wheezes are high-pitched, musical sounds produced by narrowed airways, often occurring during expiration.