When we think about diagnosing heart disease, the first thing that comes to mind is the characteristic sound with which the doctor applies an instrument to the patient’s chest. Many people mistakenly believe that this device has one single name, but in medical practice various terms are used to designate similar, but technically different devices. Understanding the difference between them is necessary not only for future doctors, but also for everyone who monitors their health.
The main instrument that allows you to hear heart sounds, pericardial friction noise or pathological murmurs in blood vessels is often simply called the “doctor’s tube” in everyday life. However, professional terminology requires greater precision. Phonendoscope and stethoscope - these are the two words that most often appear in answers to the question of what the object for listening to the heart is called, but they have design differences.
In this article we will analyze in detail the history of the creation of these devices, their structure and operating principle. You will learn why modern doctors prefer combined models and how to properly use this instrument to obtain reliable auscultation results.
Historical excursion: from paper tube to high-tech gadgets
The history of the creation of an instrument for auscultation dates back to the beginning of the 19th century. Until this point, doctors resorted to direct auscultation, placing the ear directly on the patient's body, which was unhygienic and inconvenient, especially when examining obese people or patients of the opposite sex. The turning point was the invention of René Laennec in 1816.
Legend has it that a French doctor, embarrassed to put his ear to the chest of a young patient, rolled a piece of paper into a tube and was surprised to find that the sounds of the heart and breathing were heard much more clearly and loudly. He later created the first wooden prototype, which he called stethoscope (from the Greek “stethos” - chest and “skopeo” - look). This device was a monocular wooden tube.
⚠️ Attention: Early models of stethoscopes were rigid and transmitted only low-frequency sounds, limiting diagnostics. The use of wooden instruments in modern medicine is prohibited due to the impossibility of high-quality sterilization.
The evolution of the device continued when, in the 1850s, the American physician Arthur Leared introduced a binaural (two-ear) version with flexible tubes. This allowed the doctor to hear sounds in both ears, which greatly improved localization of the source of the noise. Later, in the 1890s, Italian physician Fortunato Schiappone improved the design by adding a membrane, ushering in the era phonendoscopes.
Stethoscope and phonendoscope: what is the fundamental difference
The question “what is the name of the subject for listening to the heart” is often perplexing due to confusion in the names. In fact, the difference lies in the design of the head of the device and the frequency range of the sounds captured. Over time, these two devices have merged into one universal model, but it is necessary to understand their differences.
Classic stethoscope equipped with a hollow cup (bell), which fits tightly to the body. This design is ideal for capturing low-frequency sounds: heart sounds, murmurs in large vessels and intestinal peristalsis. The sound wave is transmitted through an air column inside the tube directly to the doctor's ears.
In turn, phonendoscope has a flat membrane at the end, tightened like a drum. When the membrane is pressed against the skin, it vibrates in response to sound vibrations. This design filters out low frequencies and enhances high frequencies, allowing you to hear better:
- 🫀 Pleural friction noises when breathing
- 🔊 High-pitched heart sounds (for example, clicks of valves opening)
- 💨 Noises in blood vessels (carotid noise)
- 🩺Wheezing in the lungs due to pneumonia or asthma
Modern medical instruments are most often combined. The head of such a device has two sides: one with a membrane (phonendoscopic) and the other with a cup (stethoscope). Switching between modes is done by rotating the headband 180 degrees, which blocks the air flow in the unused part.
The structure of a modern diagnostic device
Regardless of the name, any quality auscultation device consists of several key elements. Understanding their purpose helps to operate the instrument correctly and avoid mistakes when listening.
The first element is headband (or bow). It is made of metal and connects two ear olives. The design should be flexible enough to provide the correct pressure on the ear canal without causing discomfort. The olives are usually directed forward, along the auditory canal.
Second element - sound-conducting tubes. They can be single or double. Double tubes intertwined with each other better isolate external noise and prevent the tubes from rubbing against each other, which is especially important in noisy emergency room conditions. The length of the tubes is usually from 50 to 70 cm.
Third element - head (chest part). As mentioned above, it can be membrane, cup-shaped or a combination. The head material (plastic, steel, aluminum) affects thermal conductivity and acoustic properties. Some models are equipped with a “non-chill” system that prevents the feeling of cold upon contact with the patient’s skin.
⚠️ Attention: Incorrect position of the olives in the ears (pointing backwards) sharply reduces audibility. Always make sure that the olives point towards the nose and not the temples.
Electronic stethoscopes: the future of cardiology
Technological progress has also affected the seemingly conservative area of auscultation. Electronic stethoscopes are becoming increasingly popular among cardiologists and physicians. They are equipped with built-in microphones and amplifiers that allow you to increase the volume of sounds tenfold.
The main advantage of such devices is the ability digital signal processing. The device can filter out extraneous noise (such as the noise of clothing rubbing or conversations in the hallway), leaving only pure heart sounds. This is critical for clinicians with hearing impairments or when working with overweight patients where traditional methods are ineffective.
Many models such as Littmann CORE or 3M Littmann Electronic, can record sounds to internal memory or transmit them in real time to a smartphone via Bluetooth. This allows you to:
- 📱 Share the recording with colleagues for consultation
- 📊 Save a history of changes in the patient’s sound picture
- 🎓 Use recordings for educational purposes for students
- 🔍 Perform spectral analysis of noise using software
Why haven't electronic stethoscopes replaced mechanical stethoscopes?
Despite the advantages, electronic models require a power source (batteries), are heavier, can distort the natural timbre of sound, and cost 10-20 times more than their classic counterparts. In addition, they are sensitive to moisture and shock.
Auscultation technique: how to listen to the heart correctly
Having a quality tool is only half the battle. The second half is the correct technique for using it. Auscultation of the heart is carried out in a certain sequence of points where the various valves and parts of the heart are best heard.
The patient can be in a sitting or lying position. In some cases, to better identify diastolic murmurs of the mitral valve, the patient is asked to turn on his left side. In contrast, listening to the aorta often requires standing or sitting with a forward bend.
The doctor sequentially applies the head of the device to five main auscultation points. It is important to press the membrane or cup firmly, but without excessive pressure, against the skin, avoiding hair or clothing getting under the head, as this will create artifacts.
☑️ Heart auscultation algorithm
When using a membrane, the pressure must be sufficient to create a sealed contact. When using a cup (stethoscope mode), the pressure should be minimal so as not to stretch the skin, otherwise it will begin to act as a membrane and cut off low frequencies.
Comparison table: tool characteristics
To systematize information about what the subject for listening to the heart is called and how it differs, it is convenient to use a comparison table. It will help you quickly navigate the types of devices.
| Characteristics | Classic stethoscope | Phonendoscope | Electronic stethoscope |
|---|---|---|---|
| Main element | Cup (bell) | Membrane | Microphone + speaker |
| Frequency range | Low Frequencies | Treble | Wide (customizable) |
| Energy source | Not required | Not required | Batteries/Accumulator |
| Sound recording | Impossible | Impossible | Possible (digital) |
| Cost | Low / Medium | Average | High |
A universal choice for the general practitioner is the combined mechanical stethoscope-phonendoscope, which combines the advantages of both designs.
Care and maintenance of the diagnostic tool
Medical instruments require regular care. It's not enough to just know what it's called; it must be maintained in working order. Olives should be regularly wiped with alcohol, and the tubes should be checked for cracks through which air can pass, impairing hearing.
The membrane must be changed as scratches appear or loss of elasticity. A damaged membrane distorts the sound. To clean the internal channels of the head, you can use special brushes, but this must be done carefully so as not to damage the internal partitions.
⚠️ Attention: Never leave the stethoscope in direct sunlight or near heating devices. The plastic of the tubes can become sticky and break, and the metal parts can become scalding hot.
It is better to store the device in a straightened form, without bending the tubes at an acute angle to avoid creases. It is optimal to keep it in a special case or robe pocket, protecting it from dust and mechanical damage.
Frequently asked questions (FAQ)
Can a regular stethoscope be used to measure blood pressure?
Yes, a mechanical tonometer requires the use of a phonendoscope (or combination device) to listen to Korotkoff sounds. The membrane mode is preferable here for clearly hearing the onset of pulsation.
Why do doctors warm the head of a stethoscope before touching it?
Metal and plastic parts of the appliance may be cold at room temperature. Sharp contact with a cold head causes a reflexive contraction of the patient's muscles, which can distort heart sounds and create interference.
What is the difference between heart tone and heart murmur?
Heart sounds are the normal, rhythmic sounds of valves slamming (I and II sounds). A murmur is an additional, often longer-lasting sound that occurs when blood flows turbulently through narrowed or damaged valves, which is a sign of pathology.
What is the name of the device that not only listens, but also shows the heart on the screen?
This device is called an echocardiograph (ultrasound of the heart). Unlike a stethoscope, it uses ultrasound waves to visualize the structure of the heart in real time.
Is it possible to listen to the heart through clothes?
Strongly not recommended. The fabric of clothing creates an additional layer that muffles sounds and creates friction artifacts. For high-quality auscultation, direct contact with the skin is necessary.