Final answer:
The bell of the stethoscope is best used for auscultating low-pitched heart sounds such as the S3 and S4 sounds, which can indicate conditions like congestive heart failure or left ventricular failure respectively.
Step-by-step explanation:
The bell of the stethoscope is specifically designed to auscultate low-pitched heart sounds. These include sounds such as S3 and S4 heart sounds. The S3 sound, sometimes referred to as the 'Kentucky gallop', may suggest congestive heart failure if heard in an older individual, whereas the S4 sound is associated with stiff or hypertrophic ventricles, indicating potential left ventricular failure and described as the 'Tennessee gallop'. The bell of the stethoscope is placed against the skin to pick up these lower frequency sounds that are produced by the mechanical function of the heart, like the closing of the atrioventricular valves and ventricular filling, which may be indicative of various heart pathologies