The lung sounds are best heard with a stethoscope. This is called auscultation.
Normal lung sounds occur in all parts of the chest area, including above the collarbones and at the bottom of the rib cage. Using a stethoscope, the doctor may hear normal breath sounds, decreased or absent breath sounds, and abnormal breath sounds.
Absent or decreased sounds can mean:
- Air or fluid in or around the lungs (pneumonia, heart failure, pleural effusion)
- Increased thickness of the chest wall
- Over-inflation of a part of the lungs (emphysema can cause this)
- Reduced airflow to part of the lungs
There are several types of abnormal breath sounds. The 4 most common are:
Rales are small clicking, bubbling, or rattling sounds in the lung. They are believed to occur when air opens closed air spaces. Rales can be further described as moist, dry, fine, and coarse.
Rhonchi are sounds that resemble snoring. They occur when air is blocked or becomes rough through the large airways.
Wheezes are high-pitched sounds produced by narrowed airways. They can be heard when a person breathes out (exhales). Wheezing and other abnormal sounds can sometimes be heard without a stethoscope.
Stridor is a wheeze-like sound heard when a person breathes. Usually it is due to a blockage of airflow in the windpipe (trachea) or in the back of the throat.