The murmur of aortic insufficiency is uncommon. The first and second heart sounds occur normally, but a high frequency diastolic murmur begins with the second heart sound. The murmur characteristically diminishes in intensity after its onset and is called a decrescendo diastolic murmur. Notice how the normal heart sound pattern is disrupted by this high frequency diastolic murmur. Listen to the murmur of aortic insufficiency placed at slow speed and then increased to a normal rate.