Stethoscope

Stethoscope
Modern stethoscope.
The stethoscope is an acoustic medical device for auscultation, or listening to the internal sounds of an animal body. It is often used to listen to lung and heartsounds. It is also used to listen to intestines and blood flow in arteries and veins. In combination with a sphygmomanometer, it is commonly used for measurements of blood pressure. Less commonly,"mechanic's stethoscopes" are used to listen to internal sounds made by machines, such as diagnosing a malfunctioning automobile engine by listening to the sounds of its internal parts. Stethoscopes canalso be used to check scientific vacuum chambers for leaks, and for various other small-scale acoustic monitoring tasks. A stethoscope that intensifies auscultatory sounds is called phonendoscope.Current practice
Stethoscopes are often considered as a symbol of the doctor's profession, as doctors are often seen or depicted with a stethoscope hanging around their neck.

Types of stethoscopesAcoustic
Acoustic stethoscope.
Acoustic stethoscopes are familiar to most people, and operate on the transmission of sound from the chest piece, via air-filled hollow tubes, to the listener'sears. The chestpiece usually consists of two sides that can be placed against the patient for sensing sound — a diaphragm (plastic disc) or bell (hollow cup). If the diaphragm is placed on the patient,body sounds vibrate the diaphragm, creating acoustic pressure waves which travel up the tubing to the listener's ears. If the bell is placed on the patient, the vibrations of the skin directly produceacoustic pressure waves traveling up to the listener's ears. The bell transmits low frequency sounds, while the diaphragm transmits higher frequency sounds. This 2-sided stethoscope was invented byRappaport and Sprague in the early part of the 20th century. One problem with acoustic stethoscopes was that the sound level is extremely low. This problem was surmounted in 1999 with the invention of...