Introduction: Binaural Earbud Microphone AKA Holophonic, 3d Stereo, Bin-aural Microphones. for Less Than $10
"The Ear Mic"
In this Instructable I will show you how to create a pair of Binaural Microphones that can be worn in your ears. All you need is an old pair of Earbuds, 7 bucks and some basic soldering skills.
I use these all the time with my camera, some of the best stereo recording you can get for a fraction of the cost.
What is Bin-aural audio you may ask?
"Binaural recording is a method of recording sound that uses two microphones, arranged with the intent to create a 3-D stereo sound sensation for the listener of actually being in the room with the performers or instruments."
Essentially this effect is possible because of how our brain interprets the sound that we hear. The subtle changes in how long it takes for sound to reach one ear before another and the intensity of that sound allows our brains to interpret where that sound is coming from and how far away it is. It's incredable that this can be replicated with only two microphones, but we also only have two ears.
Listen to this famous audio clip "Virtual Barber Shop" with your headphones on to experience the effect.
Step 1: What You Need
The project is fairly simple as is the parts list.
Earbud: Free - $20 (preferably the ear wrap style, normal ear-buds will not work as well if you intend to wear these.) I believe this is similar to the pair I used .
2 x PC-Mount Condenser Microphone Element: - $3.19 can be found at Radio Shack. Heres A link .
Packing Foam: Free - ??? Not sure where to buy the stuff. It is optional, used as a a good wind screen.
Soldering Iron with solder.
Wire stripper or scissors
Hot glue gun
Step 2: Disassemble Ear-Bud
This will vary from ear-bud to ear-bud of course, but essentially your just going to take the ear-bud apart as delicatly as possible to get access to the speaker inside. For mine I believe it was just a matter of popping the thin metal wind screen out (upper right of picture). The rest came apart pretty easily because most of it was flexible rubber.
Now, un-solder the two wires from each of the two speakers.
Step 3: Attaching the Microphone
You will notice that there are different colors to the wires.
Since we are changing these from an output device to an input device it will actually flip the two channels. so left becomes right and right becomes left.
Right Speaker (left mic)
Left Speaker (Right mic)
green or black: Positive
This will actually work to our favor because you will actually have to wear these ear buds backwards anyways, because instead having a speaker pointed inward you will have a microphone pointed outward, savvy? (pictures may help)
So find out where the ground and positive wire is located on your new microphones(sometimes says on box) and solder the proper wires to the proper locations.
Before we go any further it may be a good idea to plug these in and test them to make sure that they are working right. If they are not then simply switch the wires around.
I use Audacity (It's Free! and one of the best audio programs)
Just plug them into the back of your computer and give em a go. Go on, I'll wait...
If they work then Hot glue over the wires to ensure that they don't wiggle loose.
Step 4: Reassemble
Do they work? Great!
Now to reassemble the pieces. Odds are your windscreen won't fit back in, if it does great, if not no worries make a better one using foam.
I hot glued the speaker into place and cut a cube of packing foam to use as a windscreen. I carefully avoided the microphone and hot glued around the plastic edge and glued the foam down. I then used my dremel to shape the foam into a dome-like shape
I don't have a photo of the back, but I ground down some of the sharper bits of plastic with my trusty dremel so that it fit more comfortably in my ear(be careful not to go too deep and damage the wires).
Step 5: Enjoy!
I love using these with my video camera, I recommend panning your camera with your head to your recorded video matches your audio. They make the best stereo microphones at a fraction of whats being sold right now. Also these are vary sensitive, so use a low sensitivey setting for your audio( if your camera has that option).
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Here are some of my own test samples.
Wear Headphones to get the proper effect
First with the ear-buds worn on my head
Then with the ear-buds secured to the sides of a mannequin head.
And then I took some test footage with them being worn on my head and plugged into my camera. (really crappy video for some reason, I must have used the wrong encoding... but its the audio that's important)