In this recording, listen for an opening snap that begins about 75 milliseconds after the commencement of S2. Such opening snaps in early in diastole and a single S2 can mimic a split second heart sound.
The source of an opening snap is thickened valve leaflets which produce a snapping sound when opening. The more severe the thickening the earlier in diastole the opening snap occurs.
Listen

The patient's position is supine.
Visualize
Observe
An opening snap is caused by thickened valve leaflets. When they open, it produces a snapping sound.
The more severe the thickening the earlier in diastole the opening snap occurs. In this example, you are hearing an opening snap which occurs 75 milliseconds after the start of the second heart sound.