Public Safety Training Facility
Monroe Community College
Rochester, New York
Normal Heart Sounds
Examine the illustration and play the WAV file multiple times. It is more important to learn the cadence (the rhythmic sequence or flow of sounds) than the quality of the sounds at this point.
Remember and review the cardiac events as you listen. S1 is created when the ventricles contract and close the mitral and tricuspid. The left ventricle is capable of generating higher pressures more quickly and the mitral valve will close slightly before the tricuspid. The two sounds slightly overlap and create one sound - S1. In reality, the first half of S1 is the mitral component and the second half of S1 is the tricuspid contribution. If you listen to your own heart for long periods every night for many nights, you can eventually get to a point where you can appreciate both components of S1. For now we will be happy if you can identify which sound is S1 and which is S2. At this rate (50 bpm) it is easy. S1 is always after the longer pause. As heart rates increase, systole time remains the same and diastole time shortens. At faster heart rates it becomes more difficult to distinguish between S1 and S2. A useful aid is to keep a finger on the patients pulse. Note the tracing on the previous page (the pulse is felt between S1 and S2 at the neck). The pulse tracing in the illustration is slightly delayed due to the distal site where it was recorded.
Once you have S1 mastered, listen to this WAV file again and concentrate on S2. the two valves that produce this sound are aortic and pulmonic valves in that order.
Return to Heart Sounds
Updated: September 23, 1997