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Stethoscope Information & FAQs

Learn more about auscultation and 3M™ Littmann® Stethoscopes

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General Stethoscopes

I can't hear anything out of my stethoscope. Is something wrong with it?

If the acoustic performance seems to be lacking or absent, visit Use of Your Stethoscope for tips to optimise your stethoscope's performance.

Do 3M™ Littmann® stethoscopes contain latex?

No. 3M Littmann stethoscopes do not contain natural rubber latex or dry natural rubber as components or in the product or packaging.

Can any 3M™ Littmann® stethoscope be used during an MRI?

No. All our stethoscopes contain metal.

What are the advantages of using a tunable diaphragm?

Using a tunable diaphragm allows you to listen to both low and high frequency sounds without the need to remove the chestpiece from the patient and turn it over repeatedly. By varying the pressure placed on the patient, a tunable diaphragm will adjust, or tune, the sounds to allow you to hear either low or high frequencies. When holding the tunable diaphragm on a patient and pressing lightly, low frequency sounds will be transmitted. When using the tunable diaphragm and pressing firmly, higher frequency sounds will be emphasized. This convenience will save you time and allow you to focus on your patient instead of trying to determine if you should be listening to the bell or diaphragm side of the chestpiece.

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Cleaning and Care

What stethoscope replacement parts are available?

See Parts for more information. Parts may be purchased from our Retailers.

How should I routinely clean my mechanical or electronic stethoscope? Can I sterilise it?

Littmann recommends cleaning the stethoscope in-between every patient with a 70% isopropyl alcohol solution or wipe. Do not immerse your stethoscope in any liquid or subject it to any sterilisation process. For more information on cleaning both electronic and mechanical stethoscopes, see Cleaning and Care.

Why does the tubing on my stethoscope become stiff and rigid after a period of years?

The majority of tubing used on 3M™ Littmann® stethoscopes is made of PVC (polyvinylchloride), which becomes hard when exposed for long periods of time to the lipids found in human skin. If worn around the neck, we recommend wearing the stethoscope over a collar away from contact with your skin.

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Product Information

Can I still get the 3M™ Littmann® Cardiology II S.E. Stethoscope?

No. The Littmann® Cardiology II S.E. Stethoscope has been discontinued. However, the Paediatric side of the 3M™ Littmann® Cardiology III™ can be easily converted to a traditional bell like the Littmann® Cardiology II S.E.

After removing the tunable diaphragm of the Littmann® Cardiology III™, replace it with the nonchill bell sleeve included in the spare parts box. Slip the bell sleeve over the edge of the bell and fit it into place.

Can I use the 3M™ Littmann® Classic II Infant Stethoscope on neonates?

Yes. However, some neonatal specialists report that the diameter of the bell and diaphragm on this model is still too large to get good surface contact.

How is the 3M™ Littmann® Classic II S.E. Stethoscope different from the original 3M™ Littmann® Classic II Stethoscope?

The S.E., or Special Edition, features a tunable diaphragm in place of the Classic II's standard floating diaphragm.

Can I replace the floating diaphragm of my Littmann® Classic II or Littmann® Cardiology II with a tunable diaphragm in order to use the tunable diaphragm effect?


Every time I switch on my Littmann® Model 3000 electronic stethoscope, it starts on a very loud (or very low) level. It was not like this when I bought it.

The default volume setting may have been accidentally changed. You can reset it to the volume level that is most effective and comfortable for you by first selecting that volume level, and then pressing the PLUS or MINUS button until you hear a double beep sound. The stethoscope will start at that volume level each time you turn it on and until you program it differently. Changing the volume during auscultation will not affect the preset volume setting you have established.

What are the advantages of an electronic stethoscope?

Many heart and lung sounds that are difficult to hear for a variety of reasons can be potentially missed even with normal hearing. Amplification along with ambient noise reduction helps you hear the sounds you need to hear.

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Electronic Stethoscopes

What is proprietary ANR Technology?

Littman® Model 3100 and Model 3200 stethoscopes cancel out, on average, 85% of ambient background noise that can interfere with the auscultation experience, without eliminating critical body sounds. So you're much less likely to miss the sounds you need to hear in noisy work environments; a full 13% better than previous models.

3M™ Littmann® Model 3100 and Model 3200 stethoscopes were designed to accommodate three battery types to fit your needs. Use one AA Alkaline, Lithium, or NiMH battery to operate your electronic stethoscope. The default battery type is Alkaline. Therefore, if using either a Lithium or NiMH battery, you must change the battery type within the setup menu of the electronic stethoscope for a reliable battery life indication on the display screen. The Lithium battery is a non-rechargeable cell that is recommended for low-temperature operation of the stethoscope and generally has a longer life than an Alkaline battery. The NIMH battery is a rechargeable battery (external charger required).

What type of battery does the stethoscope use?

3M™ Littmann® Model 3100 and Model 3200 stethoscopes were designed to accommodate three battery types to fit your needs. Use one AA Alkaline, Lithium, or NiMH battery to operate your electronic stethoscope. The default battery type is Alkaline. Therefore, if using either a Lithium or NiMH battery, you must change the battery type within the setup menu of the electronic stethoscope for a reliable battery life indication on the display screen. The Lithium battery is a non-rechargeable cell that is recommended for low-temperature operation of the stethoscope and generally has a longer life than an Alkaline battery. The NIMH battery is a rechargeable battery (external charger required).

If the battery is depleted will the electronic stethoscopes function as a non-electronic stethoscope?

No. The electronic stethoscopes will not work without the battery.

Why I am having trouble hearing anything when using the stethoscope?

It is important that you are wearing the stethoscope properly. All Littmann stethoscopes have headsets that are angled and are designed to fit properly with your ear canals. When holding the stethoscope, be sure that the headset is pointed towards the ceiling and then when placing the headset in your ears, be sure that the headset is pointed towards your nose.

How can I improve the sound quality during auscultation?

When using the 3M™ Littmann® Electronic Stethoscope Model 3100 and Model 3200, there are several techniques that are important to consider that can substantially improve your auscultation experience.

The sound sensor, where all sound acquisition occurs, is quite small and located in the very centre of the chestpiece (for demonstration purposes, you can peel off the diaphragm and look for the indentation under the white sticker). The area around the sound sensor does not contribute to sound acquisition. Therefore, it is important to focus the point of contact with the patient on the very centre of the chestpiece.

Only light contact is necessary with the Littmann® Model 3200. This includes both the handling of the stethoscope and the contact on the patient. Excessive pressure on the patient may result in artifact sounds.

Contact with the patient must remain steady and consistent for optimal sound quality. Movement with the chestpiece will induce frictional noise. It is a best practice to start your auscultation exam at a lower amplification level. Then, if you are trying to listen to a difficult to hear sound, adjust the amplification upward. Using the amplification on an as needed basis will help reduce distracting noises during your exam.

Finally, it is important to recognise the difference in technique between non-electronic stethoscopes and the 3M™ Littmann® Electronic Stethoscopes. Holding the Littmann® Model 3200 lightly, making light contact with the patient, focusing the point of contact on the centre of the chestpiece, and remaining steady will assure the highest sound quality auscultation experience.

How long is the battery life? Can I do anything to extend it?

The 3M™ Littmann® Model 3100 and Model 3200 battery will last for approximately 60 hours of continuous use (depending on Bluetooth® usage, you may experience a shorter battery life with Model 3200). Before the battery is depleted completely, you will hear a warning tone that the battery has only two more hours of continuous use. 

The life of the battery is being conserved if you are seeing the Littmann® logo; you are in standby mode. To enter active mode, tap on the diaphragm or push a button. To turn off the stethoscope, either do nothing (the stethoscope will power off after a period of time that is based on the POWER setting) or push the power button for two seconds (preferred).
There are several options to maximise battery life.1) minimising backlight display time will conserve battery life. Select Menu > BACKLITE and then select either DISABLE or ON DMND (on demand). DISABLE will completely disable the backlight at all times. With ON DMND, the backlight will only activate after pressing the power button. If you feel the backlight is necessary in order to read the display screen, simply select Menu > BACKLITE > ALWAYS. This will activate the backlight at half power to provide visual assistance, yet minimise power consumption. 2) Ensuring the Auto On / Auto Off feature is enabled (should be by default) will preserve battery life. This feature can be customised to allow for different periods of time before entering standby mode. To optimise the battery life, select Menu > POWER > LOW. This will program the stethoscope to enter standby after 10 seconds of inactivity.

Sound quality remains constant even on low battery. The electronic stethoscope will not work without a battery.

What is Bluetooth® technology?*

Bluetooth® wireless technology is a short-range communications technology intended to replace the cables connecting portable and/or fixed devices while maintaining high levels of security. The key features of Bluetooth® technology are robustness, low power, and low cost. The Bluetooth® specification defines a uniform structure for a wide range of devices to connect and communicate with each other.

Does My Computer Need Bluetooth®?

No. Included with the purchase of the Littmann® Model 3200 is a USB Bluetooth® adaptor (dongle). Simply connect the Bluetooth® dongle to your PC using the USB port and your computer will be Bluetooth® enabled. For optimum performance, it is recommended that you use a wireless dongle which was included with the Littmann® Model 3200.

What is the range of the Bluetooth® i.e. how far away can the Littmann® Model 3200 be from the PC and still communicate via Bluetooth®?

The Littmann® Model 3200 uses a Class 2 Bluetooth® link, with a maximum range of 10 meters (about 30 feet). The Bluetooth® range will be reduced when objects (walls, furniture, people, etc.) are in-between the Littmann® Model 3200 and the PC. To improve Bluetooth® communication, reduce the distance and/or allow a line of sight between the Littmann® Model 3200 and the external device.

How can I optimise Bluetooth® wireless performance?

For optimum wireless connection performance, it is important that the stethoscope chest piece and wireless dongle are in close proximity and that the path between them is free of any obstructions. Walls, furniture, and bodies will degrade the wireless signal.

The positioning of the stethoscope and wireless adapter is crucial to good wireless performance. In some cases, the use of a USB extension cable which elevates the adapter and/or changes its orientation can result in a marked improvement. Littmann® recommends using the StarTech Desktop USB Extension Cable, or similar device, that can be found online at many retailers or at your local electronics store.

During recording, it may help for the PC to be located next to the patient (rather than behind them) so that the patient's body does not block the signal path. Hold the chest piece firmly with fingertips (rather than a cupped hand) to allow the wireless antenna to function optimally. minimise the distance between stethoscope and PC. Under typical conditions, a distance of 10 feet should be readily achievable.

Operating environment also plays a role in connection performance. Cordless phones, cellular phone accessories, microwave ovens, and computer WiFi equipment may all degrade connection performance and should be considered if connection performance is less than desirable.

Is Bluetooth® safe to use in a hospital environment?

The Bluetooth® system employed by the 3M™ Littmann® Model 3200 stethoscope and software is a Bluetooth® Class 2 wireless data link that operates at a frequency of 2.4GHz and with a maximum transmit power of 2.5mW. The maximum radio frequency field strength generated by the stethoscope is below three volts per meter, a level that is considered safe to use with other medical devices.

Many scientific Bluetooth® coexistence studies performed by 3M and other institutions and have shown that Bluetooth® does not interfere with other wireless devices/technologies. In addition, Bluetooth® is strongly supported by Continua (SIG group for Telemedicine) and a new Bluetooth® Health Device Profile (plug-and-play BT communication protocol for medical apps) was just recently established and the first compliant products are now available. Further, devices with similar technology to ours have been approved in other critical-care settings, including OR suites and ICU floors.

Can I connect the Littman® Model 3200 stethoscope to my Bluetooth hearing aid?

No. The Littmann® Model 3200 electronic stethoscope is not compatible with any Bluetooth hearing aid devices.

Why can't I hear the sounds when playing a previous recording from my PC?

By default, the sound will be played directly back to the 3M™ Littmann® Model 3200 via Bluetooth®. Listening to previously recorded sounds using the Littmann® Model 3200 is recommended, as the sound quality will be identical to what you heard while recording. If the connection icon is green (on StethAssist™ or Cardioscan®), try increasing the audio volume by pressing the "+" on the stethoscope.

If the "play to PC" checkbox is checked, then the sound will be played via the PC speakers instead of the stethoscope. Because of the low frequency sounds involved in auscultation, computer speakers (especially native laptop speakers) may have very poor audio response giving the impression that sounds are not playing. If "play to PC" is selected, the use of headphones typically works well. Desktop speakers will allow you to hear the recording, but will typically distort the low frequency sounds. The best alternative for playing the recorded sounds to an audience is to use a speaker system with midlevel speakers and a subwoofer.

How do I transfer sounds to a PC and can I transmit and receive sounds securely?

The sound files are transferred via Bluetooth® communication. Bluetooth® is a secure method of file transfer. Files transferred via Bluetooth are encrypted and can only be read by the PC that is connected to the 3M™ Littmann® Model 3200 stethoscope.

How Do I Connect my 3M™ Littmann® Model 3200 to StethAssist™ using Bluetooth?

In order to transfer data between two Bluetooth® devices, they must first be "paired" electronically. Pairing is a discovery and authentication process that allows your Bluetooth® equipped Littmann® Model 3200 stethoscope to communicate with another Bluetooth® equipped device and establishes the link between these two devices as a trusted pair. While StethAssist can remember trusted pairing with up to eight different Bluetooth® devices, it will only communicate with one paired device at a time. In addition, you cannot pair a Littmann® Model 3200 with a second Littmann® Model 3200.

Once paired, the Littmann® Model 3200 can connect to the PC running StethAssist. Select the CONNECT option by pressing and releasing the (M) button. The LCD screen will signal that the Bluetooth® link is active. The stethoscope will automatically return to operational status.

How do I clean my 3M™ Littmann® Model 3200 stethoscope?

Your Littmann stethoscope is designed to provide years of reliable service. We recommend following our stethoscope cleaning and care (link to guidelines) guidelines to keep your Littmann in optimal condition.

How do I install the 3M™ Littmann® StethAssist™ Heart & Lung Visualization Software?

First, insert the USB Bluetooth® adaptor (dongle) into your PC. Next, place the StethAssist™ CD in the CD-ROM of your PC and follow on-screen instructions for installation and stethoscope connection. If the installation process does not start automatically, click on the Setup.exe file on the CD. If using a work computer, contact your IT Department to install the software on your computer. Once installed, the software will guide you through the pairing and connecting process.

What is StethAssist™?

StethAssist™ is software intended to be used with the 3M™ Littmann® Model 3200 electronic stethoscope for the recording and display of heart sounds and other physiological acoustic signals. StethAssist™ works with the Littmann® Model 3200, and runs on a PC meeting the specified requirements.

How durable are the electronic stethoscopes?

The 3M™Littmann® Model 3100 and Littmann® Model 3200 were subjected to splash tests, drop tests, cleaning tests, button press tests and other rigorous testing to ensure it could withstand even the toughest conditions. The chestpiece's solid, cast-metal construction and durable chrome finish can stand up to years of wear and tear. The Littmann® Model 3100 and Littmann® Model 3200 are validated to operate at -22°F to 104°F (-30°C to 40°C) and a relative humidity range of 15 - 93%.

Every time I turn on the stethoscope, I have to change the amplification. Can I set a different default amplification level?

Yes. Select the amplification level you would like to set as default. Press the M button, then press the "-" button until SET VOL is selected, and then press the M button again. The default amplification has now been changed to the new level and is indicated by a small mark in the vertical line next to the volume bars.

Every time I turn on the stethoscope, I have to change the filter type (Bell or Diaphragm). Can I set a different default filter type?

Yes. Select the filter type you would like to set as default. Press the M button, then press the "-" button until SET FLTR is selected, and then press the M button again. The default filter type has now been changed to the new selection.

Will the Littmann® Model 3100 and Littmann® Model 3200 work on Infants and small children?

The Littmann® Model 3100 and Littmann® Model 3200 were designed to auscultate people of all sizes, including infants and small children. The acoustic sensor is 15mm in diameter, about the size of a small button or dime and is located in centre of the chestpiece. Therefore, when auscultating a patient, you only need to be concerned about making contact with the very centre of the chestpiece to achieve optimal sound quality.

Why does the heart rate display appear inconsistently?

When trying to obtain the heart rate of a patient, it is important that the very centre of the chestpiece is making good contact with the patient, as this is the location of the sound sensor. It takes five seconds of consistent heart sounds to compute the initial heart rate and updates are provided every two seconds. The heart rate will then be displayed for 10 seconds after removal of the chestpiece from the patient. Prior to the initial reading, the display shows two dashes (--).For heart rates outside a range of 30-199 bpm, the display will also show two dashes (--).

The acoustic-based heart rate display functions best when the Littmann® Model 3100 or Model 3200 is placed near the apex of the patient’s heart and can be monitored while using any filter mode and/or volume level. If the heart rate changes from consistent to inconsistent or if there is excessive ambient noise, patient movement or lung sounds during auscultation, the heart rate will display two dashes (--). With practice, your ability to obtain a heart rate from your patient will improve. The heart rate feature was designed and validated for us on humans.

Can I engrave my stethoscope?

While 3M does not provide engraving services, several Littmann® retailers will engrave your stethoscope. Please consult with our retailers directly.

Where do I find pricing information?

Find retailers. Pricing may vary between Retailers.

What is the warranty of the electronic stethoscopes?

Two-year eartip-to-diaphragm warranty.

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