One way a person is able to hear his own heart is with a stethoscope. According to Dictionary.com, René-Théophile-Hyacinthe Laënnecinvented invented this simple medical instrument in France in1819. Later modifications added two earpieces connected by rubber tubing to the bell.
American Diagnostic Corporation indicates that many stethoscopes in use in 2014 have a dual head, having one side as a bell and the other as a diaphragm. To select the side for use, the individual turns the bell. Gently tapping on one side of the stethoscope with the earpiece in place allows the user to determine the active side. To listen to the heart, the active side of the stethoscope is pressed to the chest firmly.