I wanted to learn to take my blood pressure, but when I tried using this stethoscope I could not hear anything, even right over my heart. I figured it was user error. But then I came here and I see that many others have had the same problem. This stethoscope seems to work when I tap on the diaphragm, or use it on a mechanical watch, but not for a heartbeat. My wife had the same problem. The earpieces are also very uncomfortable.