Listening to heart sounds dates as far back as the 1700s when Jean Baptiste de Senac, a physician to King Louis XV of France and the author of the first known text on cardiology, used auscultation and percussion for diagnosis. A stethoscope that amplifies auscultatory sounds is called a phonendoscope or electronic stethoscope. Abnormal sounds are called murmurs. Some murmurs are functional, i.e., they are harmless and do not affect cardiac function. Others are signs of disease, such as when the valves do not close properly due to stenosis or cardiomyopathy. Other causes of murmurs are heart defects, such as atrial septal defects, which is a hole in the wall between the two atria. The objectives of the studio are to: learn the basics of auscultation, understand the operation of an electret microphone, learn data acquisition into a computer, and compute and plot the power spectrum of digitized signals.