Two distinguishable sounds can be heard during the cycle of the beating heart when listened to with a stethoscope. The heart sounds are usually described as a lup-dup sound. These sounds are due to the closing of the valves of the heart. Unusual heart sounds are called murmurs.
Update Date 5/13/2014
Updated by: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, Washington. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.