Five hundred repetitions of four basic cardiac murmurs significantly improved auscultatory proficiency in recognizing basic cardiac murmurs by medical students. These results suggest that cardiac auscultation is, in part, a technical skill.
The Heart Sounds Tutorial by Blaufuss.org is a fancy flash-based simulator with animations. The McGill University Virtual Stethoscope is another useful website. Click here for more web-based teaching resources for hearts sounds from UCLA and breath sounds from Loyola University.