Compact, Consumer “Stemoscope” Recently Launched: A Medgadget Review

While it is not intended to be used as a medical device or diagnostic tool, Hulu Devices has created a stethoscope for consumer use. The device itself looks like the head of a stethoscope, and is about the size of a watch face. Connection to this device is via Bluetooth to the Stemoscope app that can be downloaded onto your smartphone. Pairing is quick and painless, simply involving scanning a QR code printed on the diaphragm piece.

This device is appropriately named the “Stemoscope,” as it is designed for science, technology, engineering, and mathematics (STEM) education. However, the company has shown the device being used for other purposes, such as listening to a pet’s heart beats or even to the sounds of a tree.

From a relative standpoint, we compared the Stemoscope to the Littmann Classic III and Littmann Master Cardiology stethoscopes that are widely used in healthcare. In regular patient care, the head of the stethoscope serves to listen to both high pitch and low pitch sounds. Typically, the “bell” is best for detecting lower pitch sounds, such as heart murmurs or bowel sounds, while the diaphragm is best for listening to higher pitched sounds, such as normal heart sounds and breath sounds. Thus, as expected, the Stemoscope app offers these same corresponding modes, as well as a third mode:

  1. Bell mode (20-200 Hz)
  2. Diaphragm mode (100-500 Hz)
  3. Extended range mode (20-1000 Hz)

In actual practice, the Stemoscope’s bell mode picked up low- to medium-pitched sounds with reasonably good correlation to what can be heard with the Littmann stethoscopes. However, the diaphragm mode did not seem to be quite as sensitive to the higher pitched sounds as the Littmanns. Finally, as expected, the “extended range mode” seemed to be a combination of the sounds heard from the two other modes.

What did seem effective was the normalization and clean up of noise artifacts by the app’s algorithms once the Stemoscope was securely positioned such that the output was clear after waiting a few seconds. We would recommend using headphones (possibly noise-cancelling ones) for the best listening results, as the sounds are not heard as clearly if played using the phone’s internal speakers. Other features included: 1) the ability to record sounds by tapping a suggested placement position in the app, 2) suggested placement positions for listening to the heart or lungs, or even to your dog’s heart, and 3) the option of emailing the sound recording.


This device launched on Kickstarter this week, and at a $24 pledge amount ($40 retail value), does not break the bank. The Stemoscope is sensitive enough to pick up more pronounced sounds fairly clearly – especially for educational purposes that do not require extensive distinguishing of more subtle heart sounds.

Here’s a video introducing the Stemoscope at Kickstarter:

Device info page: Stemoscope…

Kickstarter campaign: Stemoscope, Listen to the Sound of Life…