Introduction: How to Record Binaural Audio Tracks With a Homemade Mic

This Instructable will show you how to very simply create a stereo microphone set for
BINAURAL RECORDING.

Binaural recording is a technique of recording sound with two microphones approximately
as far apart as your ears (facing outward obviously) on a rig, mannequin head or maybe just worn like earphones for when your listening to something you want to remember.when listened to in stereo headphones this type of recording can help you accurately gauge the direction of the sounds you are listening to by ratio of volume in each ear, creating the kind of realism you don't get anywhere else, which makes this project great for recording things like meetings you want to remember with any clarity as it will remind you of where everyone around was sitting giving your memory the jolt it sometimes needs, it is also great for music technicians and blog/vloggers as you can record and know where the drummers, guitarists and of course singers are in comparison to the microphones when listening over and let your viewers know where you are in comparison to your camera/ mic when blog/vlogging.

Step 1: The Parts

You will need for this Instructable:
*1 set of broken or no longer used stereo earbuds with an ordinary audio jack
*2 small basic Radioshack mic's (mine were salvaged from some walkie talkies.
*Some solder (a soldering iron and some basic skill might also come in handy)
*Some hot glue (and maybe a glue gun (both optional)
*And some wire strippers (or just use your nails as I sometimes do)
*And that's it

Step 2: Audacity

While I personally use audacity and recommend it.
(You can download it here http://audacity.sourceforge.net/)
you can use any. The reason I recommend audacity is because of it's freeness
and functionality.***
Anyway when your'e using it it will display any noise received by the mic's when theyr'e plugged in, making it a very useful way of testing you have got the polarity right on the mic's by holding the wires against the pins before soldering thus avoiding the need to unsolder it and resolder it correctly this time (please learn from my mistakes so you don't have to make them).

***If you disagree with this statement of opinion feel free to have long conversations with each other about it in the comments section below and feel assured that I will ignore any petty crap you care to come up with on the topic but will of course also listen to anything constructive.

Step 3: Snip, Strip and Solder (the Main Bit)

now taking your earbuds/earphones carefully snip the heads off before going on to
strip the wires, underneath you will find two wires which need to be soldered to the mic's pins (remembering to test first though), you have now replaced the tiny speakers with tiny
microphones which when plugged in should come up as left and right in audacity. once you've soldered the pins you can add some hot glue to cover any exposed wires and stop short circuits.

Step 4: Mic Placement

While this project can be simply held up with some wire this causes more sound to travel to the microphone on the other side of the rig than would normally if there was a head in the way, (remember the objective here is realism). one of the best ways is to attach it to a mannequin head (a foam hairdressers one for wigs is best as you can easily cut grooves or holes within which you shall place the mic's. ask your local hairdresser where you can obtain one from (you might have to ask them to get one for you as a lot of hairdressers buy supplies from outlets only members can buy from).

 The other good method is to attach them to either side of your head with medical tape (dont use duct tape as it isn't made for skin) which you can find in your local supermarket (walmart probably if your'e American) it will be a good idea to attach them in front of or behind your ears so as not to obstruct the passage of sound to your own ears preventing you from hearing what you are recording.

Step 5: Audacity Again

To record on audacity:
*First Make sure you've got the left and right mic's the correct way around by speaking
into them in turn and seeing which comes up with sound on the screen (to avoid doing this twice mark them in some way)
*Go into project
*Click "new stereo track"
*Press the big button with the red dot (record)
*If all went well you should be recording in two channels (left and right obviously)
and have binaural sound. (If you are using the rig or the mannequin head you can plug in some headphones and listen to this effect while recording)
*Now go and ENJOY

Comments

author
MarcoS196 (author)2017-03-11

Hello,

If one is interested in the DIY route, they can find 3D printed anatomically accurate ears with ear canals here:

https://www.shapeways.com/shops/binaural-microphone-ears

There is also an explanation of why anatomically accurate ears and ear canals are essential for accurate recordings.

author
FelixK34 (author)MarcoS1962017-04-22

Surely it depends how you listen back. If you are using in ear headphones then yes you want the sound to have been filtered through anatomically correct ears but if you are listening with over ear headphones which is generally the better sounding option anyway surely you would want to record the audio from just outside the ear because the sound will be filtered by your own ears anyway.

author
MarcoS196 (author)FelixK342017-04-23

Felix.

What you are describing is a spaced pair recording with a baffle in between, not unlike the Jecklin disc recording technique.

The aim of binaural recordings (which the spaced pair with Jecklin disc is a somewhat crude approximation of) is to encode into the left and right microphones the same sound waves that would hit the eardrums if your head were in place of the mannequin head.
Recording at the ear opening doesn't achieve that (the HRTFs are not complete, so the brain is missing important cues to localize and recognize sounds).

I get where you're coming from but I think what you're probably skipping is this fundamental step in binaural recording: the raw recording needs to be processed through a filter that accounts for the soundwave being passed through two sets of ears (the microphone and your own). This filter balances the frequency content so that it sounds natural during playback, while making sure that the differences between left and right microphone signals are all the same ones that the eardrums would experience if they were in place of the microphone capsules when the recording was made. This is fundamental to achieve realism.

A simple experiment one could try is this: record something with a head with just the pinna replicas and then record it after adding simple ear canals made out of plastic tubes (about 2.5 cm long).
You will see that the 3D sound stage is much better reproduced when the canal is added, and the sound is more realistic too.
The only thing you have to be aware of is that the equalizations to apply to the two recordings are different.
However, the procedure to find that equalization is the same. Some people use a different procedure, but what I do is I reverse the frequency response measured from each microphone when a white noise signal is played through the respective loudspeaker individually.
Ex: play white noise through right loudspeaker only. Analyze frequency spectrum recorded by right microphone (this will be different in the case of with or without ear canal), reverse it and apply it to right microphone during the mixing phase.
Same process for the left ear.
Logic and MatchEQ can be used to do the above, for example.

Hope this helps...

author
JosephK145 (author)2017-01-09

Can someone help. I feel this guide isn't very clear. Also, could a
dual microphone set be modified to record left and right respectively?

Look at these from Amazon. Two mics ready to go, however each one is recording L and R at the same time. Can they be modified so they only record one channel respectively?

mics2.PNG
author
masters42 (author)2015-10-08

Question -- does this require any specialized audio input? I thought that the minijack hardware for most mic ports is only mono. My desktop has the standard audio on the motherboard- speaker out (stereo), mic in, and line in. I have yet to build this project but have the parts on their way.

author
seal308 (author)2015-09-16

I tried making it but it didn't work for me.

Audacity only recognized my computers own built in microphone.

author
DanielC10 (author)2014-11-26

Question: would unidirectional, or omnidirectional mics be best for this? I could understand arguments for both.

author

It would not matter if you use the correct technique.

As long as the mics are placed in the ear so that the tones reflected by the folds and parabola of the ear are picked up without the mics being "in the way" to get a best unaltered sound recording. Of course the best way to achieve this is to make a set of your own ears out of plaster, and insert the mics from the inside to the ear canal entrance, easy to hand drill the plaster, point the mics to the back of your head - as the sound from the front of us is actually reflected sounds from the ears parabola, its not a direct sound, most binaural mics do not take this into account. (have a close look at your ear canal). I've been making (and brain storming) binaural mics (not really mics but should be "ears") for a well over a year now. check out http://awi3d.plus.com for my on going 3D projects if you enjoy binaural audio.

author
TrollFaceTheMan made it! (author)2014-06-27

I made it, and can confirm it works. I opted for bendy mics, so I can wrap them around my ears. Very cool thanks agian!

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author
TrollFaceTheMan (author)2014-06-27

Cool Instructable, thanks!

author
saimasaima (author)2014-04-11

Will electret microphones work for this project? Something like this: http://www.digikey.com/product-search/en?v=433&mpart=EM-6050P

author
ijibang (author)2012-09-27

Thank you very much for sharing your knowledge. Will try out this as one of my weekend projects. Will fiddle with Audiocity first.

author
Magentadinosaur (author)2012-04-06

thank you so much for this post!! my friend and i have been exploring binuaral audio, but we've just been introduced to it in our last year at school and are on the brink of losing access to the equipment we've been using.
this is an amazingly cheap way to continue our projects.

author
msantos12 (author)2011-10-22

fantastic idea ..i will try

author
TSC (author)2010-11-16

Good idea!!!

author
techy-man (author)TSC2010-11-16

Thank you.
Have you tried it or were you just looking?
because if you're interested in the concepts of binaural just youtube search "binaural" and you'll get alot great recordings and ideas.

author
TSC (author)techy-man2010-11-16

OK Your welcome!! No I was just looking!!!

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