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Encyclopedia > Stethoscope
Look up stethoscope in Wiktionary, the free dictionary.

The stethoscope (Greek στηθοσκόπιο, of στήθος, stéthos - chest and σκοπή, skopé - examination) is an acoustic medical device for auscultation, or listening, to internal sounds in a human or animal body. It is most often used to listen to heart sounds and breathing. It is also used to listen to intestines and blood flow in arteries and veins. Less commonly, "mechanic's stethosopes" 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. Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ... Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... For the chemical substances known as medicines, see medication. ... Auscultation is the technical term for listening to the internal sounds of the body, usually using a stethoscope. ... Front of thorax, showing surface relations of bones, lungs (purple), pleura (blue), and heart (red outline). ... Breathing transports oxygen into the body and carbon dioxide out of the body. ... The intestine is the portion of the alimentary canal extending from the stomach to the anus and, in humans and other mammals, consists of two segments, the small intestine and the large intestine. ... Section of an artery For other uses, see Artery (disambiguation). ... In the circulatory system, a vein is a blood vessel that carries blood toward the heart. ...



Early stethoscopes
Early stethoscopes

The stethoscope was invented in France in 1816 by René-Théophile-Hyacinthe Laennec. It consisted of a wooden tube and was monaural. His device was similar to the common ear trumpet; indeed, his invention was almost indistinguishable in structure and function from the trumpet, which was commonly called a "microphone." In 1851 Arthur Leared invented a binaural stethoscope, and in 1852 George Cammann perfected the design of the instrument for commercial production, which has become the standard ever since. Cammann also authored a major treatise on diagnosis by auscultation, which the refined binaural stethoscope made possible. By 1873, there were descriptions of a differential stethoscope that could connect to slightly different locations to create a slight stereo effect, though this did not become a standard tool in clinical practise. Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Year 1816 (MDCCCXVI) was a leap year starting on Monday (link will display the full calendar) of the Gregorian calendar (or a leap year starting on Saturday of the 12-day slower Julian calendar). ... René Théophile Hyacinthe Laënnec René-Théophile-Hyacinthe Laennec (February 17, 1781- August 13, 1826), French physician; inventor of the stethoscope. ... Trumpeter redirects here. ...

Rappaport and Sprague designed a new stethoscope in the 1940s which became the standard by which other stethoscopes are measured. The Rappaport-Sprague was later made by Hewlett-Packard, later Philips, and today there are still cardiologists who consider it to be the finest acoustic stethoscope.[citation needed] Several other minor refinements were made to stethoscopes until in the early 1960's Dr. Littmann, a Harvard Medical School professor, created a new stethoscope that was lighter than previous models. The Hewlett-Packard Company (NYSE: HPQ), commonly known as HP, is a very large, global company headquartered in Palo Alto, California, United States. ... Philips HQ in Amsterdam Koninklijke Philips Electronics N.V. (Royal Philips Electronics N.V.), usually known as Philips, (Euronext: PHIA, NYSE: PHG) is one of the largest electronics companies in the world, founded and headquartered in the Netherlands. ... David Littmann, M.D., (1906-1981) was a cardiologist and Harvard Medical School professor and researcher[1]. His name is well-known in the medical field for the patented Littmann Stethoscope reputed for its acoustic performances for auscultation. ... Harvard Medical School (HMS) is one of the graduate schools of Harvard University. ...

Current practice

The stethoscope is used in aid of diagnosing certain diseases and conditions. The stethoscope is able to transmit certain sounds and exclude others. Before the stethoscope was invented, doctors placed their ear next to the patient's body in hopes of hearing something.

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.

Stethoscopes are also used by mechanics to isolate sounds of a particular moving engine part for diagnosis.

Stethoscopes are sometimes used by safe-crackers to hear the tumblers inside the combination, to ultimately learn the combination to a safe.

Types of stethoscopes


Acoustic stethoscopes are familiar to most people, and operate on the transmission of sound from the chestpiece, via air-filled hollow tubes, to the listener's ears. 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 produce acoustic 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 by Rappaport and Sprague in the early part of the 20th century. One problem with acoustic stethoscopes is that the sound level is extremely low. Acoustic stethoscopes are the most commonly used.


Electronic stethoscopes overcome the low sound levels by amplifiying body sounds. Currently, a number of companies offer electronic stethoscopes, and it can be expected that within a few years, the electronic stethoscope will have eclipsed acoustic devices.

Electronic stethoscopes require conversion of acoustic sound waves to electrical signals which can then be amplified and processed for optimal listening. Unlike acoustic stethoscopes, which are all based on the same physics, transducers in electronic stethoscopes vary widely. The simplest and least effective method of sound detection is achieved by placing a microphone in the chestpiece. This method suffers from ambient noise interference and has fallen out of favor. Another method, used in Welch-Allyn's Meditron stethoscope, comprises placement of a piezoelectric crystal at the head of a metal shaft, the bottom of the shaft making contact with a diaphragm. 3M also uses a piezo-electric crystal placed within foam behind a thick rubber-like diaphragm. Thinklabs uses a stethoscope diaphragm with an electrically conductive inner surface to form a capacitive sensor. This diaphragm responds to sound waves identically to a conventional acoustic stethoscope, with changes in an electric field replacing changes in air pressure. This preserves the sound of an acoustic stethoscope with the benefits of amplification.

Noise reduction

More recently, ambient noise filtering has become available in electronic stethoscopes, with 3M's Littmann 3000 and Thinklabs ds32a offering methods for eliminating ambient noise.

Recording stethoscopes

Some electronic stethoscopes feature direct audio output that can be used with an external recording device, such as a laptop or MP3 recorder. The same connection can be used to listen to the previously-recorded auscultation through the stethoscope headphones, allowing for more detailed study for general research as well as evaluation and consultation regarding a particular patient's condition and telemedicine, or remote diagnosis. . Laptop with touchpad. ... For other uses, see MP3 (disambiguation). ... Auscultation is the technical term for listening to the internal sounds of the body, usually using a stethoscope. ... Telemedicine may be as simple as two health professionals discussing a case over the telephone, or as complex as using satellite technology and video-conferencing equipment to conduct a real-time consultation between medical specialists in two different countries. ...

See also

A fetal stethoscope (also known as Pinards stethoscope or a pinard) is a listening device used in the care of pregnancy. ...

External links

Wikimedia Commons has media related to:
  • BBC: Smart stethoscope for detecting kidney stones

  Results from FactBites:
stethoscope - Encyclopedia.com (1090 words)
stethoscope [Gr.,=chest viewer], instrument that enables the physican to hear the sounds made by the heart, the lungs, and various other organs.
The earliest stethoscope, devised by the French physician R. Laënnec in the early 19th cent., consisted of a slender wooden tube about 1 ft (30 cm) long, one end of which had a broad flange, or bell-shaped opening.
When this opening was placed against the chest of the patient, the physician, by placing his ear against the opposite opening, could hear the sounds of breathing and of heart action.
Noise-Immune Stethoscope Helps Medics Hear Vital Signs in Loud Environments (708 words)
November 27, 2006--A new type of stethoscope enables doctors to hear the sounds of the body in extremely loud situations, such as during the transportation of wounded soldiers in Blackhawk helicopters.
Modern electronic stethoscopes have raised the maximum tolerable noise level to 90 decibels to 95 decibels by replacing the ear pieces with loudspeaker inserts that provide a better seal with the ear canal and replacing the tubing with electrical cables that do not pick up acoustic noise.
Where an acoustic stethoscope yields a "lub-dub" sound from a heartbeat, with the first beat being the strongest, an ultrasound stethoscope will yield a "ta-da-ta" pattern, with the second beat being the strongest.
  More results at FactBites »



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