Bone Conducting Earphones

Intro: Bone Conducting Earphones

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. 

Comments

[TheOsmWeirdo]

If the sound can be made louder and clearer by using an amp then Can anyone tell me how much amplification do we need(o/p of amplifier in terms of watts) ?

[TeDv8]

wattage is really low, but a normal opamp isn't really the right option for serious amplification, since it is basically a capacitor instead of a coil. so instead of increasing current you need to increase voltage. increasing current might make the sounds more correct on higher frequency however. so you can use any amplifier, but for high volume you will need to add a small transformer coil, most likely a air gab one, or one with a really small core.

[Gönn_dir_hart]

Just use an opamp and experiment with the resistor by using a potentiometer

[sparhawk7]

any ideas on how to do this stereo rAther than mono? or how to mount it? so far all i have is using an old pair of headphones or the sound reducing kind. not earbuds, but the earcovering kind of stuffs. or maybe a sweatband. i'm using the little vibrator from cellphones to see if that works.

[moddinghomer.]

I know i am late, but you could use two discs instead of one to have stereo sound instead of mono

just pretend that each disc is another version of the earbud itslef

[jelte1234]

It would work, however please remember that the sound is REALLY quiet using this method. I'd see this more as a cool demo than as something functional. For that, you'll need an amp.

[sparhawk7]

sunglasses would work. if you added tension to it so the back bit pressed them against your ear. also, just a word of advice, using peizos(especially cheap ones) are always going to sound thinner and not get your bassy low end as much, simply because they're better at making high pitched sounds. studio quality speakers use peizo stuff to augment their tweeters.

[sparhawk7]

also, AMAZING JOB, i take it this is your first instructable? it's really well thought out and explained. very good job.

on a side note... does anybody else think it's strange that instructable is un derlined in red squiggley to signify mispelled... on Instructables.com?

[sparhawk7]

spelling misspelled wrong.... *shakes head in shame* sorry everyone...

[JasonM42]

The sound is quite soft but the concept works. Pretty cool when I touch the piezo to another surface and you can start hearing music.

[Jeph Diel]

hey, from your comment I take it you built one. how is the sound leakage with one of these? how easy is it for someone else to hear while using it on full volume(or perhaps with an audio amplifier)?

[JasonM42]

May have replied to this under jmedd as well : I didn't use an amp so the sound is very low when connected to a my laptop audio port. I had to hold anything making the noise close to my ear to hear the sound. The iPod didn't have enough power to create any vibration however.

There is some slight sound coming off the piezo disk even when it is not touching anything but there is a noticeable effect when you attach it to something to conduct the vibration.

I plan to add a 3w amp to this to see what type of improvement I can get.

[jmedd]

I didn't use an amp so the sound is very low when connected to a my laptop audio port. The iPod didnt have enough power to create any sound.

There is some slight sound coming off the piezo disk even when it is not touching anything but there is a noticeable effect when you attach it to something to conduct the vibration.

I plan to add a 3w amp to this to see what type of improvement I can get.

[chilli-tech]

I get factories to make our Bone Conduction Headphones but I think I'm going to give this a try myself! Awesome!

[gsable6]

He its not working at all what to do any suggestion how to make it

[mike.freeman.549]

You can tweak this project by combining an amplified speaker circuit with a low cost, ready-made headset here: http://igg.me/at/cynapsmint. The 'standalone headset' option can be connected directly to a powered speaker output for a sleek, suped-up version that can reach 120dB of rich output

[plmp]

Hi, I made this using dc motor, do you know, how to increase the volume? It´s incredibly low...

[bneo99]

Just a random idea, i wonder is it worth adding a headset amplifier like the CMoy amp to boost the signal and also im planning to buy piezo disks to make this. Should I get the ones with lower resonant frequency?

[amesj]

Why wouldn't you want a higher voltage for a better sound?

[A_Steingrube]

Depends. If the voltage rating on the piezo element is too high, you will not get a full range of sound (your higher frequencies and mids will likely get cut off). If the voltage rating is too low, you risk blowing the element when you turn up the volume.

You also want to avoid getting larger piezo elements as the larger they are, the more likely they are to bend and then break (the element is a crystal, after all).