How does a stethoscope work?

The stethoscope is an acoustic device that amplifies body noise to achieve its best perception and therefore the integration of various signs, which are mainly auscultated in the heart, lungs and abdomen and also called a stethoscope, currently the most used stethoscopes are the littmann, is an acoustic device used to hear the internal sounds of the human or animal body.

It is generally used in the auscultation of heart sounds or respiratory noises, although sometimes it is also used to objectify intestinal noises or murmurs by abnormal blood flows in arteries and veins. The exam using the stethoscope is called auscultation. They are part of the semiology of General Medicine to the various specialties.

What is your history?

The word stethoscope originates from (stethoscope) whose word Sthetos means breasts and Skopein indicates examining. Pulmonary auscultation is the semiological method that immortalized Laennec. Indeed, TheophileHyacinthe Laennec was the inventor in 1816 of the stethoscope.

Its creation was the monoauricular stethoscope that consisted of a kind of initial funnel, made with sheets of resistant material and finally, a wooden instrument similar to a flute which he called a cylinder and later, stethoscope.

What is auscultation?

Auscultation is the action of listening to visceral acoustic phenomena. These are vibratile energy that emanates from elastic bodies. Acoustic phenomena are divided into: a) Tone: it is the most elementary, a simple vibration. b) Sound: more complex, more vibrations, but with a dominant one. c) Noise: a complex and heterogeneous phenomenon

What are the types of stethoscopes?

In the market there are two types of stethoscopes, acoustic or mechanical and electronic, however in this guide only reference will be made to acoustics. Within the group of acoustics, two types can be distinguished mainly: Pinard stethoscopes and biauricular or conventional stethoscope.

Biauricular or conventional stethoscope

Stethoscopes are made up of the following parts that, together, transfer the acoustic information from the body surface to the examiner’s ears: It consists of rubber tubes that end in two olive trees that adapt to the ear and also these tubes link with another which contains a diaphragm and a hoods which amplify the auscultation sounds, it is essential for the correct measurement of blood pressure in conjunction with the sphygmomanometer.

What are the parts of the stethoscope?

  • Olives The use of soft olives improves comfort, seal and durability, these are specially coated to improve lubrication and reduce dust adhesion. Available in both sizes, short and long in black and gray colors.
  • Hose set Includes olive, binaural and hose, parts available only in black. It is important that you keep in mind the model of your equipment for an appropriate purchase. The hoses can be one or two volumes depending on the model. The hose is made of PVC (polyvinyl chloride), does not contain latex or natural rubber.
  • Hoods The hoods is a fundamental part of the stethoscope, it is positioned on the part of the patient’s body or on the organ that he wishes to auscultate.

How is its operation?

It has a membrane and a hoods. Either part can be placed in the patient. The two detect the acoustic signals that travel through the tubes filled with air and reach the ears of the doctor. The hoods  transmits low frequency sounds, it is ideal for listening to the lungs. The membrane, on the other hand, detects high frequencies and allows listening to the heart. To detect the different frequencies, there are two modes: low frequencies high frequencies

Low frequencies

If you want to hear low frequency sounds (traditional hoods), you can use the open hoods or the double frequency diaphragm so that it makes very light contact on the skin.

High frequencies

If you want to hear higher frequency sounds with the double frequency diaphragm, press the hoods firmly. If you want to toggle between high and low frequency sounds without having to turn the hoods, simply vary the pressure exerted on it.

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