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Technical Description

Abstract: The stethoscope may be the one instrument common to all doctors. René Théophile Hyacinthe Laënnec (1781–1826) was a French physician who, in 1816, invented the stethoscope. Using this new instrument, he investigated the sounds made by the heart and lungs and determined that his diagnoses were supported by the observations made during autopsies. Laënnec later published the first seminal work on the use of listening to body sounds, De L’auscultation Mediate (On Mediate Auscultation). Therefore, Laënnec is considered as the father of clinical auscultation. Most heart and lung diseases are associated with and reflected by the sounds that the heart produces. Heart auscultation, defined as listening to the heart sound, has been a very important method for the early diagnosis of cardiac dysfunction. His work was acknowledged to be a great advancement in the knowledge of chest diseases.

Object and Mechanism Description


A stethoscope is a medical device or an instrument for detecting sounds produced in the body that are conveyed to the ears of the listener through rubber tubing connected with a piece placed upon the area to be examined. During the physical examination, the stethoscope can help to hear certain sounds in our bodies that cannot otherwise be heard with just the ear. It is used primarily to listen to the lungs and heart. The stethoscope helps listener to easily hear if an individual’s heart or lungs functioning properly or not?

Description: Stethoscopes vary in their design, color and material. Most are made of Y-shaped rubber tubing. The stethoscope is a total of 71.12 centimeters in length and weighs 135 grams. The body of the stethoscope is made up of the headpiece which joins with the U-shaped top part of the tubing which is two-sided to allow for insertion of the ear tubes. The tubing then narrows down to one single long tube that has the diaphragm attached at the other end.

Description of the principal parts of the stethoscope?

The stethoscope is made up of three main parts: (a) the head piece, which contains the ear tubes and ear tips, (b) the tubing, which joins the head piece and chest piece, and (c) the chest piece, which includes the stem and diaphragm.

Headset: The headset has hollow ear tubes which measure 15.24 centimeters in length. These are also called the binaural tubes. They are silver colored and made of anodized aluminum. The top part of each ear tube has a curvature inwards and a ribbed design for attachment of the ear tips. The ear tube inner diameter is 0.5 centimeters and outer diameter is 1 centimeter. The hollow soft ear tips are size medium and are gray. They are soft sealing and have an inner diameter of 1 centimeter, and outer diameter distally of 3 centimeters. They have a pear shape that tapers towards the ear tube insertion side. The ear tips also have an internal ribbed design that complements the ribbed area of the ear tubes for a tight fit and seal. These ear tips snap in place. The opposite side of the ear tubes attach to the tubing. They are held in place by a seal and a tension spring which holds the ear tubes apart. The ear tubes can be pulled or pressed together to increase or reduce the tension for a tighter or looser fit. The ear tubes can also be rotated for proper placement in the ears. Ideally, the ear tips would be slightly rotated away from the user for best function of stethoscope.

Tubing: The hollow tubing of the stethoscope is the longest part. This is also called the acoustic tube. It is made of polyvinyl chloride (PVC), and measures 50.8 centimeters in length. It has an inner diameter of 1 centimeter and outer diameter of 1.5 centimeters. The top part which is shaped like a .U. is where the ear tubes are inserted. Internally, it also contains a tension spring that is used to modify fit and hold the ear tubes together. The two separate tubes merge down into a single tube in this model. The material is flexible and soft. This is the part of the stethoscope that is Ocean Blue color.

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Chest Piece: The chest piece of this model has the stem which connects the tubing to the tunable diaphragm. It is 1.63.5 centimeters long and has an inner diameter of 0.5 centimeter, and outer diameter of 1.25 centimeters. This is made of anodized aluminum and is silver colored. The stem is also used to open the side of the diaphragm that you wish to use. To do this, the stem is rotated 180 degrees. When it is rotated, it clicks into place. The diaphragm of the stethoscope is made of machined stainless steel and is double sided. This is the part used to initially transmit sounds. It has a flat side and a side that looks like a bell with a small hole in the middle. The flat side diameter is 4.445 centimeters and used for high frequency sounds while the bell side diameter is 3.175 centimeters and used for low frequency sounds. When listening to sounds, the diaphragm vibrates and transmits air up the tubes to produce sound in your ears.

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How does a stethoscope work?

A stethoscope enhances body sounds and transmits those sounds to the listener ears. A typical model has a flat, round chest piece covered by a thin, tightly stretched skin of plastic called a diaphragm. When place the stethoscope on someone’s chest, the sound will cause the diaphragm to vibrate. Those vibrations would travel outward if the the diaphragm were a standalone device, but because the vibrating object is attached to a tube, the sound waves are channeled in a specific direction. Each wave bounces, or reflects, off the inside walls of the rubber tube, a process called multiple reflection.  In this way, each wave, in succession, reaches the eartips, or rubber nubs on the ends of the device, and finally the listener’s eardrums. So, stethoscope actually works by vibrating sound to the physician’s ears and amplifying that sound. Also, some stethoscopes must be placed directly on the skin, while others can work effectively through clothing. It’s important to understand that whether using stethoscopes to monitor a patient’s health, a doctor or nurse may need to listen in several different spaces. Using a stethoscope, a person more than 2 feet (0.6 meters) away from a patient’s chest can hear louder heart sounds than a person whose ear is in direct contact with the patient. However, never simply place the stethoscope on a patient and go by the first reading. Therefore, every physicians should make sure to listen thoroughly and carefully before finalizing a diagnosis. Examination with a stethoscope is noninvasive but very useful. It can localizing problems related to the patient’s complaints. Diagnostically, this makes the stethoscope an invaluable medical tool.

Process Description

What is auscultation?

Auscultation is the process of listening to body sounds, usually by using a stethoscope. It allows the listener to listen to the normal and abnormal sounds of the internal organs, such as lungs and heart. Use of an acoustic stethoscope to hear, interpret, and communicate findings of lung and/or heart sounds is an important skill for medical professionals involved in cardiopulmonary care. The waves of high-pitch sounds, like breath and heartbeats, are traveling at higher frequencies, meaning they cause a greater number of pressure fluctuations in a given time period. Higher-pitch sounds will directly vibrate the surface area of the large, flat disc (and the plastic disc inside). This basically means the sound waves caused by the opening and closing of an artery, for instance, are the same ones that travel through the stethoscope tubing to the listener’s ears. However, lung sounds are different from transmitted voice sounds. Lung sounds are generated within the lungs, unlike transmitted voice sounds, which are generated by the larynx. Lung sounds consist of breath sounds and adventitious, or abnormal, sounds heard or detected over the chest. Normal breath sounds are heard over the chest wall or trachea. Basically, breath sounds contains background noises, on which adventitious sounds are sometimes superimposed. Breath sounds are classified into normal tracheal sound, normal lung sound or vesicular breath sounds, and bronchial breath sound. Bronchial breath sounds are further subdivided into three types: Tubular, cavernous, and amphoric.

Here is the function of the process:

Lung: Lungs auscultation is the process of listening to lung sounds, usually with a stethoscope. Physicians and nurses commonly auscultate lungs. If anyone suffers from a breathing condition or common cold or flu, by placing the stethoscope on the lungs, can hear sounds which may give alert to inflammation and congestion.

Heart: human being heart normally beats at an even rate. By placing stethoscope, can hear abnormal heart sounds such as; a murmur, irregular rate and other sounds that might not be normal.

When and where does the process take place?

Stethoscope is mostly used in every regular health visit, in hospitals, in emergency medical service, in nursing school or in any medical fields. It also being used when measuring blood pressure, assessing lung sounds, assessing heart sounds, assessing bowel sounds, detecting bruits, measuring the span of the liver and hearing aid. It helps to amplify the internal sounds.

Who or what performs the process?

The stethoscope in an invaluable piece of equipment used by most medical personnel when assessing patients. For example, Doctors (Primary care, pediatrics, medical specialist), nurse, emergency medical services, e.t.c.

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How does the process work and the steps in the process?

Heart: Stethoscope users must learn to assess what they hear. When listening to the heart, one must listen to the left side of the chest, where the heart is located. Specifically, the heart lies between the fourth and sixth ribs, almost directly below the breast. The stethoscope must be moved around. A health care provider should listen for different sounds coming from different locations. The bell (one side of the head) of the instrument is generally used for listening to low-pitched sounds. The diaphragm (the other side of the head) of the instrument is used to listen to different areas of the heart. The sounds from each area will be different. “Lub-dub” is the sound produced by the normal heart as it beats. Every time this sound is detected, it means that the heart is contracting once.

Lung: The lungs and airways require different listening skills from those used to detect heart sounds. The stethoscope must be placed over the chest, and the person being examined must breathe in and out deeply and slowly. Using the bell, the listener should note different sounds in various areas of the chest. Then, the diaphragm should be used in the same way. There will be no wheezes or crackles in normal lung sounds.

In conclusion, the stethoscope is an essential tool/device in any healthcare professional practice. Millions of peoples lives have been saved due to this medical invention. By listening to the heart, a Doctor could diagnose different diseases of a patient based on what they hear. Without the stethoscope, millions of peoples would have suffered with the disease or died untreatenly. It truly is a timeless medical device and it has also undergone changes throughout the years for maximum functionality for the patient care.


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