Former for sound of of one mind , basically originate systaltic when the oscillatory ; latter that mitral valve and tricuspid shut generation is disloyalty sound , basically originate diastolic when the vibration that aorta valve and pulmonary artery valve shut a generation 前者为第一心音，主要来源于心脏收缩时二尖瓣和三尖瓣关闭产生的振动;后者为第二心音，主要来源于心脏舒张时主动脉瓣和肺动脉瓣关闭所产生的振动。
