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 four most common are:
Rales. Small clicking, bubbling, or rattling sounds in the lungs. They are heard when a person breathes in (inhales). They are believed to occur when air opens closed air spaces. Rales can be further described as moist, dry, fine, and coarse.
Rhonchi. Sounds that resemble snoring. They occur when air is blocked or air flow becomes rough through the large airways.
Stridor. 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.
Wheezing. High-pitched sounds produced by narrowed airways. They are most often heard when a person breathes out (exhales). Wheezing and other abnormal sounds can sometimes be heard without a stethoscope.
Ball JW, Dains JE, Flynn JA, Solomon BS, Stewart RW. Chest and lungs. In: Ball JW, Dains JE, Flynn JA, Solomon BS, Stewart RW, eds. Siedel's Guide to Physical Examination. 10th ed. St Louis, MO: Elsevier; 2023:chap 14.
Kraft M. Approach to the patient with respiratory disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier ; 2020:chap 77.
Review Date:
7/8/2023
Reviewed By:
Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.