DIY Digital Stethoscope

This app is designed to be used along with your DIY digital stethoscope.

Requirement:
Electret microphone/Collar mic
Bluetooth earphones with good bass

Device Assembly:
1. Plug the microphone into the ear-tip as shown in the accompanying image
Due to default settings of Android, you need to follow these steps in sequence
2. Plug the microphone into jack
3. Pair your Bluetooth headphones
4. Open the app

App Settings:

Ambient noise reduction is a tricky thing, the app uses 4 different processes to reduce noise. But the most significant is adaptive noise cancellation, it lets you record how noise sounds like, in your environment and cancels out that noise from the signal. However too much noise reduction will distort the signal. As speech overlaps with lung auscultation sounds, the sample noise shouldn’t be recorded with someone speaking in the background. We have developed and extensively tested the noise reduction process, striving to make the user interface as simple as possible, without using computationally taxing algorithm to ensure it works on wide range of phones without causing significant lag. Despite extensive testing we cannot assert noise reduction process won’t distort auscultation sounds in any patient, so by default adaptive noise reduction is off, if it’s too much noise you can easily switch to “Pre-recorded Noise” mode (with noise recorded by us, that we know works in a large number of situations) or you can choose “Adaptive Noise” mode in which you can record the noise specific to your environment. A noise sample of 3-5 secs suffice.

App provides you with three other settings: First is a toggle between General and Cardiac mode. While you can easily auscultate heart sounds in General mode, Cardiac mode selectively focuses on heart sounds, reducing the rest of the sounds for a better experience
Rest of the settings are sliders for volume and intensity of noise reduction

Tips
There may be friction artefacts from relative motion of chest-piece over skin, to decrease them apply the chest-piece lightly over the skin.

For more detailed description: https://diystethoscope.blogspot.com
Pre-Print link: https://osf.io/9aewz

Recent changes:
Beta v3.0