This is an example of mild aortic regurgitation which can be caused by a bicuspid (thickened) aortic valve.
The first heart sound is diminished due to premature closure of the mitral valve leaflets.
An aortic ejection click follows the first heart sound by 75 milliseconds.
S2 is normal.
Systole is silent.
A high pitched decrescendo murmur occupying the first half of diastole can be heard starting immediately after the second heart sound.
The murmur is best heard at Erb's Point and can be accentuated by having the patient sitting up and leaning forward holding his breath after expiration.
In the animation you can see the turbulent blood flow from the aorta into the left ventricle during early diastole. You can see the minimally thickened aortic valve leaflets.