Both the S1 and the S2 heart sounds are best heard using the diaphragm of the stethoscope since they are high pitched. The S1 heart sound is best heard at the tricuspid listening post (left lower sternal border) since the T1 component of the S1 heart sound is the softest. The S2 heart sound is best heard at the pulmonic listening post since the P2 component of the S2 heart sound is the softest.