This video is an animation of Third and Fourth Heart Sound Gallop. While playing the animation, observe the heart valves and blood flow, which are the source of heart murmurs.
This phonocardiogram of Third and Fourth Heart Sound Gallop can be useful in learning to recognize the heart sound. Play the sound and observe the phonocardiogram waveform (on this website, we typically show three heart beats on each phonocardiogram).