A stethoscope is a medical device for listening to the internal sounds and rhythms of the body such as the lungs and heart. It can also be used to listen to blood flow in the veins and the intestines. A single headed stethoscope typically is used for listening to the heart. The dual stethoscope has two listening surfaces. The larger side is generally used for listening for high frequency sounds in the heart and the smaller side listens to lower frequencies in the lungs.
There are many types of dual stethoscopes available for purchase and they are manufactured for use on adults and infants alike. A common dual stethoscope is the Littman stethoscope. The single headed stethoscope is sometimes called the “cardiac stethoscope” and tends to have a clearer and more focused sound. The dual stethoscope is usually made from high-grade medical stainless steel and has durable internal tubing. The diaphragm side has a tight drum-like surface to enhance sounds of the inner workings of the body.
The double-sided stethoscope was developed in the 1940s and quickly became the measure by which all other dual stethoscopes were designed. The diaphragm side, or side that is employed for listening to the heart, is the side composed of a thin drum-like film, and the smaller side is actually a concave, hollow shape and is used for listening to the patient’s breathing and lungs. The diaphragm surface serves to listen to internal vibrational waves that travel up to the ear piece of the stethoscope. The smaller, bell side works to listen to vibrations from the skin and then send them up to the stethoscope’s ear piece for the doctor to diagnose. Some of the dual stethoscopes are designed to rotate without actually turning the device over and needs to be periodically lubricated to prevent the device from grinding together and possible affecting the acoustics.
While the dual stethoscope does not have as wide a listening range as the single head stethoscope, or as sharp a sound, it is more versatile and doctors will often choose this device as their primary stethoscope. The wider side of the dual stethoscope is called the diaphragm mode side and the smaller side is called the bell mode side. The wider end is helpful when listening to irregularities within the heart. The smaller end of the dual stethoscope is typically used for listening to breathing irregularities. A physician is able to simply flip the stethoscope head over to listen to different parts of the body.