The earpiece allows for a tight seal between the user and the tubing of the stethoscope. They are commonly found in either plastic or rubber.
Ear Tubes or Binaural
The ear tubes aka binaural, help provide a rigid structure for the user end of the stethoscope. In combination with the spring they help to hold the stethoscope in the ears during use.
The tubing carries the sound waves from the chest piece to the ear pieces. Single tube and double tube designs exist with varying numbers of inner lumen.
The spring helps hold the ear tubes together and prevents the stethoscope from falling out of the users ears.
The stem serves as a connection point between the tubing and the chest piece. In some models the stem also serves as the adjustment of the valve inside the chest piece. These valves allow the user to selectively use either the bell or diaphragm.
The chest piece serves as the collection point and concentrator for sound waves from the diaphragm or bell. It is typically constructed from metal. The chest piece can range from a single head, to double head, to triple head design.
The diaphragm or larger portion of the chest piece is used for listening to high pitched sounds. Variations of the diaphragm may allow the user to adjust the sensitivity to different ranges of sounds. This is known as a tunable diaphragm. These models may not have a bell present.
The bell or smaller side of the chest piece is used for listening to low frequency sounds.