digital stethoscope works most reliably with a strong heartbeat signal. If a signal is not very strong, it may be hard to detect peaks because of inherent noise. Thus, on a few occasions, we found it necessary to get out of our chairs in the lab and run up and down the stairs a few times to keep our blood moving. It’s quite amazing how much this makes a difference. Finding the right place for the end piece of stethoscope is also very important. The strongest and most reliable place on the body that we found was the neck. We had limited success on the heart when blood flow was good. The wrist rarely worked at all. Additionally, you must be very still and quiet to use our device. Talking or movement of the stethoscope produces output far above the voltage rail of the amplifier, and the resulting heartbeat trace and BPM will not be displayed accurately. This is however inherent to any stethoscope and not unique to our project; if an old-fashioned stethoscope moves around or the patient talks when it is on his/her neck there will be mostly noise.