For heart sounds listen to the synthetic sound while reviewing this lesson.
Usually, the first heart sound is slightly louder than the second heart sound when heard in the Mitral valve area...
In this case the first heart sound is much louder than the second heart sound. This can be produced by a thickened, but still mobile, mitral valve. Look at the anatomy tab to see the thickened mitral valve leaflets.
A very loud first heart sound can be an indication of mitral stenosis.