Bone conduction is the ability to hear sounds by conducting the vibrations directly to your inner ear, bypassing the middle and outer ears. Through this process you can hear sounds underwater, with your ears closed, and while others are talking. Generally bone conducting earphones are fairly expensive, so hopefully after this tutorial you will be able to make your own for pennies on the dollar. The end product of this instructable should be mounted (somehow) to your mastoid process (the bone behind your ear that juts downward towards your neck) or between your ear and your temple.
Step 1: Materials
You will need:
* piezo-electric buzzer from radio shack
* cheap set of earbud earphones that you will utterly destroy
* soldering equipment
* wire strippers
* (optional) shrink tubing
Step 2: Take Apart the Piezo-electric Buzzer
The piezo-electric buzzer you buy will come in a hard black plastic case. Try to buy the one with the lowest voltage marked on the bag. Pry apart the case carefully and extract the circular metal disc which is the actual buzzer. Take care not to break off the soldered wires, although if you do it's not a big deal, as we will be soldering later on.
Step 3: Destroy the Headphones
Now we will dismantle the headphones. Use your wire clippers to cut off the speakers at the end of both sides of the headphones. Then strip both wires and you will find two colored wires in each earphone wire, for a total of 4 wires. In my earphones one side had a red wire and one side had a green wire, both sides having a copper wire. We will call these wires: red, green, rCopper, gCopper.
Step 4: It's Soldering Time!
Out of the piezo-electric disc will come a red and a black wire, soldered onto different points on the disc. Leave these wires on the disc, but get ready to solder some wires to the ends of the red and black wires. Group the red and green wire together and solder them to the red piezo wire (or the black one, just make sure they are on a different wire than the rCopper and gCopper wires). Now group the rCopper and gCopper wires together and solder them to the black wire. You should put shrink tubing around these soldered wires so that they don't short out and stop the current from getting to the disc. Optionally you can also put a big piece of shrink tubing around the already shrink tubed wires to tidy everything up.
Step 5: Finished!
You can now plug your earphones into your computer or your mp3 player and listen to music through your skull! You will need to place the disc either on your mastoid process or the bone right in front of your ear. The sound is pretty soft and sounds a little strange, which calls for an in-line amplifier and equalizer if you want perfect music. You can also lightly bite down on the disc and hear the music through your teeth.