I have captured the output sound and waveform of heartbeat from the circuit as instructed by my supervisor, Sir Mohd Zubir Suboh. I am using the Thinklabs Phonocardiography software to capture the output signal. Above is the waveform (click on the picture to view bigger image) and also the sound of the heartbeat that i have captured. Click play button on the above player to listen to the heartbeat.