FAQs

1. Why can’t I hear anything through my headphones?

Due to default settings of Android, you need to follow these steps in sequence, while setting up the device: 
a. Plug the microphone into jack
b. Pair your Bluetooth headphones 
c. Open the app

Check if the Bluetooth device is still paired to your mobile device or disconnected.

2. How do I reduce the background noise during auscultation?

Electronic stethoscopes are prone to higher noise levels than traditional stethoscopes. DIY stethoscope uses multiple processes to reduce interference by noise, but most efficacious is environmental noise control at source. So, just like auscultation with a traditional stethoscope, pause any unnecessary alarms during auscultation. 

While increasing the volume, first increase the volume of the earphones or the mobile device to 70-80%, before increasing the volume on the app. Volume slider on the app digitally amplifies the sound, without increasing the power output of your earphones, so signal:noise ratio is better if volume is increased on the earphones first.

Positioning the microphone within the stethoscope tubing rather than the earpiece also reduces the noise

If the ambient noise is too much, use one of the two noise reduction modes available: with the prerecorded noise profile or the adaptive noise profile

Some degree of noise is also contributed by the environmental noise directly incident upon the ear, which can be reduced by using snuggly fitting earphones, preferring headphones over earphones or using noise cancelling headphones.

3. How do I improve the quality of auscultation

Using good quality components to assemble your digital stethoscope improves the quality.. Different stethoscope give dramatically different sound output, so using a good stethoscope for your digital one, will give better output. Most of auscultation output is in low frequency bandwidth so, using earphones with good bass reproduction provides a much better auscultation experience.

About

We created the "DIY Digital Stethoscope" due to need for auscultating patients in COVID wards. Because of wearing coveralls, traditional stethoscope couldn't be used and the commercially available electronic stethoscopes are out of reach of the majority of physicians because of the high cost. Some commercially available products provide attachments for stethoscope, which are cheaper than electronic stethoscope, but are still quite costly and damages the stethoscope. The aim for this device was to create a simple, low-cost yet effective method to help physicians auscultate, and deliver highest possible level of patient care, without damaging your existing stethoscope. So, just plug in a microphone and let our app handle the rest.

Features:

• Amplification: App lets you amplify faintest sounds to your desired level, without distorting the signal. 
• Noise Reduction: The app uses 5 distinct noise reduction features, adapting to the background noise to provide clear auscultation without harming the signal. 
• Dedicated Cardiac mode for better auscultation
• Store and Share: Unlike some of contemporary devices, DIY lets you store as many recordings and share them conveniently with your colleagues.

Using this device, one can:

• Auscultate using headphones over PPE: Physicians aren't able to auscultate in most COVID wards, relying on alternative tools, but, amongst the information provided by a stethoscope, detection of a wheeze and symmetry of breath sound in a ventilated patient are perhaps the most difficult to obtain from other modalities and are the one with good interventions available.
  
  
  
• Auscultate from safe distance in OPDs
• Telemedicine: This device provides physician with the means to auscultate patients remotely. LRTI is one of leading cause of Under-5 mortality. Imagine, ASHA workers using these devices to help physicians auscultate, from a distant location and make a more informed decision regarding treatment of a child.
• Medical Education: Pair it with a speaker during playback, to allow multiple people to auscultate simultaneously, helping students understand sounds better. We all have been in a scenario where the attending consultant discovers some findings on auscultation which you are unable to appreciate. Just pair your device to a speaker and then you can objectively point out the sound of interest
• Physicians with hearing disabilities can use this device to compensate for their disability

Our aim with this device was not to create the best electronic stethoscope but a electronic stethoscope which is good enough to be clinically useful and yet frugal enough to be within the reach of most physicians. So, using components which most physicians would already be possessing and ability to preserve the stethoscope were vital. 

We did a study comparing our device with a traditional stethoscope for 100 auscultation events by multiple observers, and found that two stethoscopes had very good agreement. One of the shortcomings we found was higher noise levels in DIY stethoscope as compared to traditional. Overall, the device performs well in quiet environment like wards, but in noisy ambience, one needs to focus harder to appreciate breath or cardiac sounds. We will publish the findings of our study soon.

The app is available free of cost on the Google Play Store and we do recognise it is still a work in progress and has a long way to go before it becomes an excellent tool. That being said, the device in its current form is still good enough to be helpful in some of the scenarios mentioned above, We urge everyone using this device to caution and to share their feedback with us so we can make it better. As with any new device, the users may take some time getting used to auscultating with it. We look forward to working with interested physicians/ audio or software engineers to make this device even better. Please refer to How to section, for detailed instructions on how to set up your device.  More details on the device can be found here. 

How to

To convert your stethoscope into a digital one, you will need these items:

• An electret microphone (e.g. collar mic: Flipkart, Amazon)
• Android based smartphone
• Bluetooth headphones with good bass.

To assemble the device follow these instructions:

• Select an earpiece for the stethoscope which has a large opening such that it can fit the microphone
• Remove the foam windscreen from the microphone. 
• Fit the microphone into the earpiece, ensure a snug fit.

• Plug the jack from the microphone into the smartphone.  

• Download the DIY stethoscope app from Google Play Store.
• Pair your headphones to the smartphone.
• Open the app and press Start 
• Hold the chest piece gently over the chest to auscultate

App Settings:

Mode

The app features two different modes: "General" and "Cardiac".

"General" mode is good for pulmonary auscultation, heart sounds are heard in this mode, but these are much better appreciated in the "Cardiac" mode. 

The "Cardiac" mode uses separate filters to reduce the noise and provides you with the detailed cardiac sounds similar to that of your traditional stethoscope.

Noise Reduction 

The app has 4 independent noise reduction processes working in the background. The 5th process provides you with 3 modes: "None", Pre-recorded Noise" and " Adaptive Noise". 

In "None" mode, the 5th process is turned off and this is the default setting. 

In the " Pre-Recorded Noise" mode, the app tries to cancel out the background static, noise of fans, air conditioners from the audio output. 

The "Adaptive Noise" mode lets you record a sample of your ambient sound and then cancels that from the audio output.. 

Intensity of noise cancelling by the 5th process can be modulated by the Noise Reduction slider. However, too strong noise reduction can interfere with sounds of clinical interest and sometimes lead to artefacts difficult to differentiate from crepitations, so always start with the lowest possible setting and work your way up. 

While recording the noise sample for "Adaptive Noise" care must be taken that someone must not be speaking in the background, as speech is very similar to breath sounds, and the app tends to cancel out the breath sound if the noise sample contains speech.