undercover scientist software

Ten Tips for using iStethoscope Pro

  1. iStethoscope Pro makes your phone work just like a stethoscope. It amplifies and filters quiet sounds. You can hear any quiet noise - including your heart beat - if you place the iPhone microphone in the right place. To see where to place it, check out the videos. If you are not sure where the microphone is on your device, tap or brush different parts with your finger. When you hear a loud noise, or see the waveform jump, that's the microphone.

  2. iStethoscope Pro records continuously, but only stores the last 9 seconds. To switch between record mode and playback mode, touch the switch on the bottom left of the screen. If the app does not ask for permission to use the microphone, please delete the app and reinstall v10.01 or later, and it will ask when it first runs.

  3. When recording, you can increase the gain of the amplifier by touching the plus button and decrease the gain by touching the minus button. It's also a good idea to have your iPhone volume on maximum. But watch out - sometimes it might get loud!

  4. You can listen to the sound as you record it. On devices such as the iPhone 5 and 6 where the headphone socket is next to the microphone, try using the white Apple earphones with inline microphone - you can listen with one earphone while placing the inline mic where you need it.

  5. You can record without listening by looking at the waveform display at the bottom of the screen. A strong heart sound will be visible as the waveform jumps in time to your heart. Touch the waveform to see the blue spectrograph. Deeper sounds are on the left and higher pitched sounds are on the right.

  6. iStethoscope Pro amplifies and filters sound in real time. It uses a lowpass filter, which mostly lets low frequency sounds through. You can change which frequencies are filtered as you listen by touching the left arrow next to the stethoscope image during recording. This will bring up the filter window. Swipe the blue bars left to hear lower (bass) sounds more clearly, swipe right to hear higher pitched (treble) sounds. (The blue bars of the filter window show the exact frequency response of the low pass filter from 20Hz to 20Kz, calculated as you alter the cutoff frequency by swiping.) You can set the app to launch with a specific filter setting, or disable the filter altogether, in your iOS Settings app.

  7. When listening without headphones, sometimes the iPhone will hear itself and produce a loud feedback squeal. To prevent this, the output is automatically Muted when a loud noise is heard and no headphones are plugged in. You can unMute by touching the stethoscope image.

  8. iOS devices are now so good that you can hear heart sounds even without headphones. Record your heart, switch to playback mode, unMute the sound, then hold your phone to your ear as if making a call. You should hear your heart sound.

  9. You can email your recorded sound by touching the share button at the top-right of the screen. Your sound will also be stored in your own mailbox. You can change the format to be MP4, CAF or WAV in the Settings. Note that some older devices cannot make MP4 files so the app defaults to CAF.

  10. iStethoscope Pro amplifies and filters sound. That's all. Before you can hear your heart you must learn where to listen. Check out the videos for help!


If you have any comments, questions, or stories about how iStethoscope Pro has helped you then please

email customer support here!


iStethoscope Pro User Stories

October 2013

This App Saved My Life ! I was involved in an accident and broke my collar bone and had a huge Hematoma on my thigh. After getting a plate to repair my collarbone I asked the doctor if they should drain the Hematoma, he said they let it relieve naturally. I explained to him that I was flying to the Caribbean in a couple of months, would it be ok, he said yes.

In a couple months I flew to the Caribbean and the day after I landed had some terrible back pains, thought I had kidney stones, went to the hospital down there and they had admitted me over night. The next day they said I could go home and that I had a muscle spasm, the pain had subsided but I could feel a small wheeze like symptom in my back. I told the doctor about it and by the time him came to listen it was gone. I went back to the resort and tried to enjoy the rest of my vacation. Every night between 12:00 AM and 4 to 5:00 AM I could feel this wheezing noise from my back it was very subtle, yet nothing when I laid at the beach or anything during the day. I kept a record of everything I did,ate,drank and even what exact times this happened.

As soon as I got back to Canada I made an appointment with a doctor and told her about my situation, they did some blood tests on me and found them to be out of wack. They sent me to a specialist and they did all kinds of testing on me including lung testing and everything seemed fine. All this time I was still having the wheezing feeling at night and told them that it only happens at night but they said that didn't make much sense I also told them they should admit me over night so they would hear it and they said they couldn't do that. Back and forth I went to doctors for about two or three weeks and nothing.

One night I was laying in bed feeling the wheeze and wondered if my voice recorder would pick it up... it didn't and then I thought "I wonder if there is an app for a stethoscope and I found the Istethoscope and paid for the Pro. After learning how to use it on Youtube I was ready for the next night. The next night like clockwork there was the noise and I recorded it on my Istethoscope and emailed it to myself. The next day I called the Doctor and made an appointment with them. I showed up for my appointment and it was the same thing they couldn't hear anything, I told them I had recorded it using the Istethoscope and wanted them to listen, at first they kind of snickered at it but after listening to the noise they went and got the head doctor. He was quite amazed at the noise and ordered a CT scan with contrast dye right away.

An hour later I was in the emergency room with a Pulmonary Embolism. I feel very lucky to be here telling his story. That was Dec. 2011 If I hadn't been able to record it and show it to the doctors who knows what would have happened! Thank you Peter Bentley! This App Works! John.

January 2013

I want to share my story with you. My husband and I are both RN's. So of course we have our own top of the line stethoscopes. I found your app and thought it would be fun to have on my iphone. I was pregnant with our third little girl and thought I could use it to listen to her heartbeat.

When I was 7 months pregnant she had decreased movements. I was concerned and tried using my stethoscope to try and hear her heartbeat. I couldn't hear anything so I got the istethoscope app out and was able to hear her heartbeat. Being a nurse I knew that it should be much faster than ours so I was not concerned with the rate. I was more relieved that she still had a heartbeat. This was on the 4th of July. So the next day I call my OB and went in to have her checked out since she still was not moving.

After the doctor listed to hear heartbeat with the ultra sound machine I was sent to the hospital. She was in distress. Her heart rate was well over 260. When I told them I had used your app to listen to her heartbeat the day before they did not believe that it worked. I was able to tell them that the rate was the same as what I heard the day before. So they were able to determine she was had been in heart failure since at least the day before. I was flown by helicopter to San Francisco where she was born by emergency C section. She was resuscitated several times in the first 24 hours of her life. The doctors weren't sure she would make it. But I had faith and knew God would answer my prayers. She was in the NICU for 4 weeks and came home a few days after her due date.

I am happy to report she is now 18 months old and has been off heart medications for one year. She is truly a miracle and has no long term effects from her traumatic birth. Now all my friends have gotten the App you created as well as many of the nurses who took care of us. I want to say thank you for creating this App. It played a large role in saving the life of my little miracle, Emily.

March 2012

From the founder of wooshers, the Pulsatile tinnitus forum:

One of our group members has had success listening to the objective pulsatile tinnitus with your iStethoscope App. She's been diagnosed with superior canal dehiscence and bilateral sigmoid sinus diverticulum. She has already had surgery on one side to correct it, and is awaiting surgery on the other side. I am fascinated by this and hope to again ask others --particularly those with a similar diagnosis-- if they too can hear their whoosh with the app. She is thrilled that she can now share the actual audio sound with her doctors and everyone. This was her post:

"Do you have an iphone? The app is way cool! the Microphone at the bottom of the phone is used as the "stethoscope" you put earbud style headphones in and wear them. Then you open the app and crank the careful, just like a real steth if you've ever used one, it's LOUD...don't talk into it lol. You can listen to your heart with it by firmly pressing the bottom of the phone right where a stethoscope goes...same thing. Put it over your belly, you will hear your bowel. Put it one the sides of your ribcage or back, and you hear you lungs. Putting it all over different pulses in the body, I found my venous hum...which i already knew i had even though the doctors couldn't hear it. Right above the clavicles...I have it both sides and it goes away with certain head positions."


Who is The Undercover Scientist?

Peter J Bentley is a computer scientist based at University College London and popular science writer. Author of 8 books and this iphone application.

Check out his website here:

Or his book blog:



Thanks to Justin D'Arcy for being the tester for the iPod Touch 1st Gen and enabling version 2.03 of the program to be written. Thanks to Glenn Nordehn for his tireless support and enthusiasm.

The Undercover Scientist cartoon is copyright Stephanie Clemen 2008.

The icon stethoscope image is copyright Orlando Florin Rosu 2008.

The main stethoscope image is copyright milosluz 2008.

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