Unlike the analog stethoscope used by doctors for over 100 years, the digital stethoscope appeared in 1960. According to DataM Intelligence, a market research and business intelligence firm, the Electronic Stethoscope Market size was valued at USD 342.1 million in 2021 and is estimated to reach at a compound annual growth rate (CAGR) of 8.20% over the forecast period of 2022 to 2029. Several improvements that turn the basic digital version into a smart stethoscope are included in the prediction.
To transition the traditional analog stethoscope to a smart digital version requires several steps. These steps include digitize, amplify, combine with another sensing techniques, filter unwanted signals (i.e., noise) and develop advanced algorithm(s) to detect attributes that identify specific problems sooner. Additional steps could include enable remote analysis and display the results on a smartphone.
Over 5 years ago, Johns Hopkins researchers set out to improve the design of the digital stethoscope. To obtain the optimum signal, they used five low-frequency microelectromechanical systems (MEMS microphones inside a programmable head. This makes it easier to detect lung sounds, even if the head is not placed in a precise location on the body. However, for the best measurements, noise caused by many sources in a clinical environment including the movement of the stethoscope across the patient must be addressed. Eliminating this noise is especially important to diagnose unpredictable and irregular lung sounds that indicate possible pathologies. To solve the noise problem, a sixth microphone facing outward from the patient measures noise from the environment for noise cancellation. Then an algorithm on the stethoscope’s microprocessor removes the ambient noise from the lung sounds heard by the physician.
Available smart stethoscopes
Since Eko Devices’ Eko Core digital stethoscope was approved by the U.S. Food and Drug Administration (FDA) in 2015, the company has pioneered several improvements to its stethoscope technology. Most recently, it combined an electrocardiograph (ECG) in its Eko DUO ECG + Digital Stethoscope for healthcare professionals. 
With an FDA-cleared and clinically proven cloud-based machine learning algorithm called Eko Murmur Analysis Software (EMAS), heart sounds, phonocardiogram and ECG signals captured using Eko’s smart stethoscopes can be analyzed. The software analysis employs several methods, including signal processing and convolutional neural networks, and accesses one of the world’s largest repositories of clinically validated heart sounds for training and testing.
Detecting differences in an adult patient can be difficult, but it is even more difficult in a small child. Since parents are, in most cases, novices regarding the possible problems their child could have, a smart, connected stethoscope was developed to help parents perform lung examinations at home. With these measurements, the preliminary data can be sent directly to a pediatrist, where machine learning can help to identify potential concerns. With the help of an app on the smartphone, the smart stethoscope leads the parent through the measurement process. Instructions Include where to place the stethoscope’s head on the child and feedback on the acceptability of the noise level in the room. After measuring 6-8 points, the user gets a report with details including respiratory rate, heart rate, and whether it detected any audio abnormalities that could include wheezing, rhonci (low-pitched, rattling sounds), or crackles.
References
Electronic Stethoscope Market Size Share Growth Opportunities and Forecast 2022 (datamintelligence.com)
What are the Pros and Cons of Digital Stethoscopes – Digital Health Central
Technology: A Smart Stethoscope
A Smart Stethoscope Puts AI in Medics’ Ears – Department of Electrical and Computer Engineering (jhu.edu)
Eko DUO ECG + Digital Stethoscope (ekohealth.com)
Eko Launches Screening Solution to Help Catch Heart Disease | Eko (ekohealth.com)
A smart way of asthma monitoring (stethome.com)
