The stethoscope is commonly and routinely used in medical practice by physicians, nurses, respiratory therapists and other practitioners to obtain important information about the health of patients. In some ways this is a surprise in view of the many studies that show that observer variability is high in the use of the stethoscope. Advances in computer processing have made it possible to obtain the information contained in lung sounds more accurately and efficiently. Waveform patterns can be generated in real time that show differences between common illnesses.