Introduction: Cell Phone Stethoscope

My neighbor works at a cardiologist office and said that a big drawback of teleHealth is that the doctor can’t listen to a patient’s heart. I’ve worked out a way to record your own heartbeat using a cell phone app and a few household materials. You can text or email the mp3 file to your doctor so they can listen to your heart.

This is also a fun project to do with kids as a science demonstration.

Disclaimer: I'm not a doctor, and nothing here should be considered medical advice. If you record your heartbeat and want a medical opinion, contact your doctor and forward the sound file to them.


  • Drinking glass
  • 2 medium size balloons (dollar store)
  • Scissors
  • Earbuds with microphone

Step 1:

Cut the narrow part off the balloons.

Step 2:

Stretch a balloon over the glass and lay the microphone across it.

Note: If the balloon slips off the glass, spray some hairspray (or anything sticky) on the outside of the glass.

Step 3:

Stretch the second balloon over the top.

Plug the wire into your phone.

Step 4:

Download the free app “Hear Boost”



Note: This is a free app from US company Future Moments in Brooklyn NY. The app is free but you can pay 1.99 to enable some additional features. You don’t need these features for the Cell Phone Stethoscope, but these developers deserve a couple dollars for their work so please contribute if you find it useful!

Step 5:

Open the Hear Boost app.

Step 6:

Tap “Start Listening” and put the loose earbud in your ear. Move the glass around on your chest until you can hear a clear heartbeat. It works better if you don't press very hard. Use the volume boost slider to increase the microphone sensitivity to the best level without distortion.

Once you hear a clear heartbeat, tap “REC” to start recording.

Step 7:

When you have enough (probably 30 seconds or so) tap STOP and then tap STOP LISTENING.

Step 8:

A screen opens up with your recordings, the most recent is the one on top.

Step 9:

Tap the one you just made and listen to make sure it’s clear.

Step 10:

Tap “rename” and give it a more useful name, like your name and the date:

Step 11:

Tap “share” to send it via text or email (tap OK when it asks to compress the file to MP3)

Here's my heart and lungs:

And most of all, if you are a healthcare worker reading this, Thank You so much for everything you do!