Types of stethoscopes

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Introduction

The auscultation, or listening to the inside noises of an animal or human body, is performed with a stethoscope, which is a piece of medical equipment. It normally consists of one or two tubes connected to two earpieces, as well as a small disc-shaped resonator that is worn against the skin and transmits sound. One can use a stethoscope to listen to the noises that are produced by the heart, lungs, or intestines, in addition to the sounds that are produced by the blood flow in the arteries and veins. When monitoring blood pressure, it is typically used in conjunction with a manual sphygmomanometer.

Less frequently, “mechanic’s stethoscopes,” which are equipped with rod-shaped chestpieces, are used to listen to the internal sounds made by machines (for instance, sounds and vibrations emitted by worn ball bearings), such as diagnosing a faulty automobile engine by listening to the sounds of its internal parts. Stethoscopes are commonly used to listen to the sounds of the heart and lungs. Stethoscopes have a variety of other uses, including checking scientific vacuum chambers for leaks and performing a variety of other small-scale acoustic monitoring activities. Stethoscopes were originally developed for medical usage.

Different kinds of stethoscopes

Fetal stethoscope

A fetal stethoscope, also known as a fetoscope, is a type of acoustic stethoscope that is formed in the shape of a listening horn. In order to listen to the heart beats of the fetus, it is put against the abdomen of a pregnant woman and held there. The fetal stethoscope, which was named after the French physician Adolphe Pinard, is also often called a Pinard horn (1844–1934).

3D-printed stethoscope

A 3D-printed stethoscope is an open-source medical gadget that is intended for auscultation and is created using 3D printing. Stethoscopes are used to listen to auscultation sounds.

Dr. Tarek Loubani, along with a group of medical and technological experts, was responsible for the creation of the 3D stethoscope. The design of the 3D-stethoscope, which was developed as part of the Glia project, is open source from the very beginning of the process. During the summer of 2015, the stethoscope received extensive coverage in the media.

Because of the blockade of the Gaza Strip, there was a shortage of stethoscopes and other essential medical equipment during the conflict in Gaza in 2012, which is when Loubani, a Palestinian-Canadian, was working as an emergency physician there. This prompted the need for a new type of stethoscope, which led to the development of the 3D-stethoscope. The Littmann Cardiology 3 stethoscope, which dates back to the 1960s, served as the inspiration for the 3D-printed stethoscope that was produced by Loubani.

Acoustic stethoscope

Acoustic stethoscopes accomplish their function by transmitting sound from the chest piece to the listener’s ears through hollow tubes that are filled with air. The chestpiece typically has two sides that can be placed against the patient for the purpose of sensing sound. These sides are known as the diaphragm (a plastic disc) and the bell (hollow cup). When the diaphragm is put on the patient, the patient’s body noises cause the diaphragm to vibrate, which results in the production of acoustic pressure waves. These waves then travel up the tube and are received by the listener. The vibrations of the patient’s skin directly produce acoustic pressure waves that travel up to the listener’s ears if the bell is put on the patient. The diaphragm is responsible for the transmission of higher frequency sounds, whereas the bell is responsible for the transmission of lower frequency sounds. The tube that connects into the chamber between the bell and the diaphragm can rotate and is only open on one side. This configuration ensures that the acoustic energy is sent primarily to either the bell or the diaphragm. When the opening is hooked into the bell, it may still be seen. The diaphragm can be connected to the tube by rotating it via the head by 180 degrees. In the early part of the 20th century, Rappaport and Sprague came up with the idea for the two-sided stethoscope that we use today.

Electronic stethoscope

The low sound levels can be solved by using an electronic stethoscope, also known as a stethophone, which electronically amplifies body noises. However, the amplification of stethoscope contact artifacts and component cutoffs (frequency response thresholds of electronic stethoscope microphones, pre-amps, amps, and speakers) limit the overall utility of electronically amplified stethoscopes. This occurs because electronically amplified stethoscopes amplify sounds in the middle frequency range while simultaneously dampening sounds in the high and low frequency ranges. Electronic stethoscopes are currently available from a variety of manufacturers. In order to achieve the best possible listening experience, electronic stethoscopes require the conversion of acoustic sound waves into electrical signals. These electrical impulses can then be amplified and analyzed. Electronic stethoscopes come with a wide variety of transducers, in contrast to acoustic stethoscopes, which all adhere to the same fundamental principles of physics. Putting a microphone in the chestpiece is the quickest way to accomplish sound detection, but it is also the method that is least accurate. Because of the interference that it causes from surrounding noise, this approach is no longer widely used. Another way is to position a piezoelectric crystal at the head of a metal shaft, with the bottom of the shaft making contact with a diaphragm. This technology is utilized in the Welch-Allyn Meditron stethoscope. In addition to this, 3M uses a piezoelectric crystal that is embedded in foam and hidden beneath a thick diaphragm that resembles rubber. In order to create a capacitive sensor, the Thinklabs Rhythm 32 makes use of an electromagnetic diaphragm that has a conductive inner surface. This particular diaphragm reacts to sound waves by causing changes in an electric field rather than reacting to changes in air pressure. Heart sounds can be wirelessly transmitted to a smartphone or tablet thanks to Eko Core’s capabilities.

An electronic stethoscope can be a wireless device, a recording device, and it can provide noise reduction, signal enhancement, and both visual and audio output because the sounds are sent electronically. Additionally, it can be a device that provides both visual and audio output. Around the year 2001, Stethographics introduced PC-based software that permitted the generation of a phonocardiograph, which is a graphic representation of cardiologic and pulmonologic sounds, and the interpretation of those sounds in accordance with related algorithms. For the goals of telemedicine (also known as remote diagnosis), as well as education, each of these aspects is helpful.

Electronic stethoscopes can also be used in conjunction with computer-aided auscultation applications to analyze recorded heart sounds and determine if the murmurs heard were diseased or harmless.

Doppler stethoscope

Electronic stethoscopes that assess the Doppler impact of ultrasound waves reflected from organs within the body are referred to as Doppler stethoscopes. The Doppler effect, which causes reflected waves to shift frequency, is used to determine the location of moving objects. Because of this, the Doppler stethoscope is ideally suited for use when dealing with moving targets, such as a heart that is beating. Recent research has shown that a continuous Doppler permits the auscultation of valve motions and blood flow noises in adults that are not audible when a heart examination is performed using a stethoscope. The traditional stethoscope auscultation had a sensitivity of 58%, but the Doppler auscultation had a sensitivity of 84%, when it came to the detection of aortic regurgitations. In addition, Doppler auscultation was superior in detecting reduced ventricular relaxation compared to conventional auscultation. Because the physics of traditional auscultation and Doppler auscultation are distinct from one another, it has been hypothesized that the two approaches could mutually benefit one another. A recently created Doppler-based military stethoscope that is immune to noise has been designed for the purpose of auscultation of patients in noisy surroundings.

Recording stethoscope

Some electronic stethoscopes have a direct audio output that may be connected to an external recording device like a laptop or an MP3 recorder. This allows the user to record their findings directly into the device. The same connection can be used to listen to the previously recorded auscultation through the stethoscope headphones, allowing for a more in-depth study for general research as well as evaluation and consultation regarding the condition of a specific patient, as well as telemedicine, also known as remote diagnosis.

There are applications available for smartphones that allow users to make the device function as a stethoscope. At least one of them makes advantage of the phone’s built-in microphone to amplify sound, create a visualization of it, and send the findings via e-mail. These applications may be utilized for the sake of teaching or as novelties; nevertheless, they have not yet acquired acceptability for use in professional medical settings. In 2015, the market saw the introduction of the first stethoscope that was compatible with a smartphone application.

Conclusion