Stethoscope-Microphone

DIY—Audio Series

Inspired by Diego Stocco‘s stethoscope microphone, I bought myself a stethoscope and a couple of electronic parts and built one on my own.

List of Parts

  • stethoscope
  • 1x male XLR plug
    [Alternatively any other connector able to ‘carry’ phantom power from the recording device to the condenser microphones can be used.]
  • 2x 6mm (omnidirectional) condenser microphone elements
  • audio cable
  • short piece of thin, two wire cable
  • heatshrink

 

standard medical stethoscope

standard medical stethoscope

6mm (omnidirectional) condenser microphone elements

6mm (omnidirectional) condenser microphone elements

 

Construction

Prepare the audio cable on each of its ends by stripping off a short part of the protection around the wires, leaving the bare copper of the positive and negatire wire free, while cutting off the wire of the ground/shield. On one end of the audio cable, solder the wire carrying the positive signal to pin two (2) and the wire carrying the negative signal to pin three (3) of the male XLR plug.

For more information onn how to solder XLR connectors, please see the blog about DIY Piezo Pick-ups.

 

Carefully solder the positive wire of the additional thin, two wire cable to the positive part of the condenser, and the negative wire to the negative connection. This is a delicate procedure and requires a thin soldering iron. If the condenser microphones are exposed to the heat from the soldering iron for too long, they will break.

 

At the end, put the heatshrink over the other end of the thin wires, then solder the thin wires to the audio cable. Before applying heat to the heatshrink, test the cables by plugging these into a recording device. Remember to switch on phantom power for the test. If the condensers work fine, move the heatshrink around the soldering point of the cables and warm it in order to protect their connection.

 

Next, use a sharp knife (carving knives are good for this) to create space for the condenser microphones, fitting one each into the earpieces of the stethoscope. As long as the holes are not too big, the condenser microphones will hold all by themselves (no glue was needed for the example stethoscope here).

The last step is to test the finished stethoscope-microphone again by plugging it into the recording device and searching for the best, subtle sounds to capture.

Conclusion

Because of the monophonic nature of the stethoscope it is entirely justified to combine the thin wires both condensers and solder those to their respective wires on the audio cable—using only one XLR plug into a recording device.
In this experiment the material of the stethoscope itself was to be tested, if it would change the captured sound comign from each one of the microphones. Therefore one XLR plug had been soldered to each condenser microphone.

 

Here some recordings:

Stethoscope sounds:

Clock:

Man talking:


Rain (on metal roof):

Permanent link to this article: http://www.suzannesoundcreations.com/diy-audio-electronics/stethoscope-microphone/

9 comments

Skip to comment form

  1. Awesome, thinking about building one of these myself. Thanks for the how-to guide!! Will be sure to check out the rest of your blog.

  2. Hey Susanne,
    I’m a hobbyist in field recording. I went to school for spatial audio and computer music.

    I’ve recently been interested in trying out attaching a microphone to a stethescope similar to your blog post. I’m rather curious about how it sounds, and if there are any interesting spatial effects I can produce using two or more stethescopes reproduced over several speakers or binarually over headphones. I’m curious as to what your thoughts are about this and if you’ve tried this out.

    I noticed that the samples on the blog post are broken links. If you have some samples lying around I’d be curious to give it a listen.

    Cheers,
    Akshay

    1. Hi Akshay,

      Sorry for the super late reply.

      Sound examples work on my end. Do you want me to search for some more examples?

      Cheers,
      Suz

    • DR NAVEEN on 23rd March 2020 at 3:41 pm
    • Reply

    Hi Sir,
    i am DR NAVEEN from INDIA working for animals.That is i a veterinary doctor .want to record the heart sound and many time require to live demo on dog or cat patient with loud speaker .live.
    pl guide me as you are sound specilist.
    regards
    sincerely
    DR NAVEEN
    INDIA
    +91-9814585053(MOBLE AND WHATSSAPP)

    1. Dear Dr Naveen,

      You could connect the stethoscope microphone to an amplifier which directly connects to speakers. Are you familiar with electronics and can you solder?

      Alternatively, depending on the budget you could also buy a few parts:
      get a stethoscope and cut the pipe maybe 5-10cm above the listening end. Submerge a lavalier type microphone in the long end of the pipe. Ideally the lavalier microphone is to be connected with a minijack connector (consumer connector and therefore cheaper).
      The microphone itself needs to be connected to a pre-amp (e.g. this could be a handheld recorder with a minijack input), which connects to one speaker.

      If you are interested, drop me a message with specifications and possible budget and I will see if I can suggest something.

      Kind regards,
      Suz

    • Boris Katz on 5th April 2020 at 1:35 am
    • Reply

    Hi Susanne,

    Is it possible to use your stethoscope for medical purposes catching and amplifying with clinically good quality of the sound? Will it require a good – expensive original stethoscope or an inexpensive one will work well?

    Thank you,

    Boris

    1. Hi Boris,

      Apologies for the late reply.

      It depends. This was a prototype and the small condensers are not the best quality.
      What is the aim of the recordings you want to make? What data are you after from the recordings?

      Cheers,
      Suz

    • Bhupendra Bhate on 22nd September 2020 at 8:40 am
    • Reply

    Dear Susanne,
    I am from India. I intend developing electronic stethoscope. Can you pls. suggest which type of microphone will best suit the purpose?

    1. Hi Bhupendra,

      Nice to meet you.

      The type of microphone entirely depends on the signal you want to pick up. I have used small condenser capsules for this stethoscope, but depending on how close you can or want to get to the sound source and what type of signal you plan to pick up, you could also use electret elements.

      Either way, you will probably need an appropriate pre-amp for the microphone 😉

      Hope this helps a little?

      Cheers,
      Suz

Leave a Reply

Your email address will not be published.