Heart Sounds

The following pages are derived from Human Anatomy and Physiology and Pathophysiology of Heart Disease.

Detectable heart sounds are produced with each heart beat.  These sounds represent events of the cardiac cycle which are known as ausculatory (from the Latin ausculatare, "to listen to"), and which can be heard best in the areas shown on the diagram below.

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It is possible to use an electronically amplified microphone on the chest, to record the heart sounds.   The recording is called a phonocardiogram, which shows heart sounds as waves.

There are four heart sounds associated with the cardiac cycle, although it is only the first and second sounds that are easily heard with a stethoscope.  These two sounds are traditionally referred to as lubb (first) and dupp (second).

First Heart Sound

Second Heart Sound

Third Heart Sound

Fourth Heart Sound


Any unusual heart sound is called a murmur.  These are common in acquired and congenital heart disease, and are a useful diagnostic tool.  Murmurs can be produced by a number of different haemodynamic and/or structural changes in the vasculature, which can cause the normal flow of blood to create a noise, which can then be heard by the physician.

Murmurs are described by their timing, intensity, pitch, shape, location, etc.   The most important one is timing, which means whether the murmur is present during systole, diastole, or is continuous through both.  There is a complete grading system for qualifying the intensity of the murmur.

Systolic Murmurs

Diastolic Murmurs

Continuous Murmurs