Our first lesson presents a normal first and second heart sound. This recording was taken over the Apex (Mitral valve area. The the closing of the mitral and tricuspid valve leaflets produce the first heart sound. When the aortic and pulmonic valve leaflets close, the second heart sound is created. The first heart sound has a slightly greater intensity than the second heart sound. The first heart sound is also called S1 and the second heart sound, S2.