Teeth Headphone - Can You Hear With Your Teeth?

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Introduction: Teeth Headphone - Can You Hear With Your Teeth?

About: Technopolis, the flemisch science centre, highlights their coolest projects concerning Science, Technology, Robotics, Engineering, Arts and Mathematics on the brand new platform 'Technopolis STREAM'. Please ...

*-* This Instructable is in English. Please click here for the Dutch version,

*-* Deze Instructable is in het Engels. Klik hier voor de Nederlandse versie.

Hearing with your teeth. Sounds like science fiction? No it's not! With this DIY 'tooth headphone' you can experience it for yourself. Sound usually enters your ears and travels to the inner ear via a serious detour. But you can skip a couple of steps and hear directly with your 'bones'. Scientists call it 'bone conduction'. Read our blog (only in Dutch) to find out how bone conduction works*. Can't wait to try it yourself? Then start constructing with this Instructable!

* Don't speak Dutch? Don't worry! Here's the short version of our blog: Bone conduction skips the eardrum and the ossicles, making it possible to hear by the conduction of sound through the bones of your skull (or even your theeth). Bone conduction is the reason why your voice sounds so different when recorded (because in real life, you listen to your voice through air AND by bone conduction at the same time). Some hearing aids make use of bone conduction. And dit you know that Beethoven connected his own DIY teeth headphone to his piano to be able to keep on making music?

Step 1: Materials & Tools

Materials

  • DC motor (1.5 - 3 volts) - maybe you can demolish an old toy
  • 3.5 mm audio jack - you can also cut the jack from an old set of earphones (but please don't you dare to take the fancy new headphones of your little brother!)
  • 30 cm speaker wire (consisting of 2 wires) - when re-using a jack, leave 30 cm of speaker wire
  • A short piece of heat-shrink tubing
  • A metal rod (+- 10 mm in diameter and +- 20 cm in length) - it works well with a wooden rod too

Tools

  • Wire stripper
  • Soldering kit
  • Drill - with the same diameter as the motor axis (usually 2 mm)

Extra

  • An old smartphone, laptop, mp4-player ... with your favourite song on it

Step 2: Mount Audio Jack

*-* Skip this step when re-using a wired audio jack *-*

  • Unscrew the new audio jack and slide the case over the speaker wire, in order to be able to close the jack in the next step.
  • Strip 0.5 cm of insulation from the ends of the speaker wire.
  • Solder one cable at the middle pin of the audio jack. Cover it with the piece of heat-shrink tubing in order to prevent the cables from touching each other.
  • Solder the other cable at the outer pin.
  • Carefully close the audio jack case again.

Step 3: Mount Motor

  • Solder the other two cable ends to the pins of the motor.

Step 4: Mount Rod

  • Drill a hole in the middle of one end of the rod, making the axis of the motor fit in precisely.
  • Slide the rod over the motor axis.

Step 5: Connect Tooth Headphone

  • Connect the audio jack to your smartphone (or portable computer, or mp3-player, or …) and let your favourite song play … you don’t hear anything!

Step 6: Hear With Your Teeth

  • Now bite on the metal rod with your teeth. You can hear the music!
  • The sound improves when closing your ears.

*-* This is an experiment that shows how bone conduction works. If you're planning on using the device to actually listen to music with your brand new smartphone, we suggest you to add an amplifier (see step 8). Connecting a DC motor directly to the phone's audio output, might in some cases damage your phone. As an alternative, you can choose to mount a flyback diode between power and ground. Or you can use a piezo instead of a DC motor.*-*

Step 7: Bucket Radio

Instead of a 'teeth headphone' you can also easily turn this device into a 'bucket radio'. Hold the bottom of a cup (or beaker, or bucket) against the motor axis. The music vibrations are now transferred to the can, amplifying the sound.

Step 8: Amplify Music (extra)

Probably, you heard the music play very softly. You can give it a boost by adding a little amplifier. Amplifiers are sold in electronics store, or you can solder one yourself if you’re into electronics (search for ‘small amplifier kit’ in your favourite search engine).

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    user

    We have a be nice policy.
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    14 Comments

    I am def in my right ear from infections when I was a child. My hearing through bone conductance is very good in that ear. A few years ago I was fitted with a hearing device called “Sound bite.”. It had a receiver transmitter in my right ear that looked like a regular hearing aid. A receiver transducer clipped to the molars in my mouth and was invisible . It used a piezoelectric device that vibrated through me teeth and skull, the results were amazing. My brain even pecieced bi directional between my good ear and skull. Simply amazing! The bad news is the company whent out of business and mine broke. No I don’t want a titanium stud sticking out the back of my head. My point is there is s market for millions of us who have only one good hearing ear. Someone take over where others dropped the ball. There is a market. Thank you for your efforts!!

    2 replies

    Thank you for your story. Would those bone conducting headphones work for you at all? I guess you need a good "microphone" part of a hearing aid or something for the "input."

    I have conductive headphones and they do work. Yes a microphone connection through my iPhone 7 Plus would be good for some applications.

    I remember adverts for 'bonephones' in the 70's. They went round your neck like a travel pillow.

    Muy buen instructable. Felicidades y Danke!

    Something to consider

    If you remember how your teeth can hurt a bit after Ultra Sonic cleaning, it is because the vibration actually loosens them a small amount.

    Though this in only short term your teeth heal from the cleaning.

    Prolonged use may not be a good idea. I REALLY think you should ask a Dentist if this is OK or not.

    1 reply
    user

    yes i agree it does not seem a good idea for long term use. i suggest a better idea: you can try the skull to "hear" (behind the ear for example) vibrations.

    YES!

    Please read our comment about counter electromotive force...

    This is a cool solution.

    You can also use a piezo to resonate the bar, which is a little safer than hooking the motor into your phone's output.

    https://www.instructables.com/id/Turn-Nearly-Anyth...

    If you are going to stick with the motor, I would put a diode (backwards) between power and ground to handle any unforeseen electrical spikes.

    1 reply

    Brilliant idea!

    But, I would never consider connecting the DC motor directly to the audio jack. As far as I think, you should connect the motor to a small amplifier. (Just to be on the safe side).

    1 reply

    Thanks for your reply.

    We just wanted to show that it works with cheap DIY components and that the amplifier is not really necessary to make it work. Please check our comment with more explanation about counter electromotive force.

    !! IMPORTANT !! When you connect a DC motor directly to the phone's audio output, you could damage your phone!

    Here's why:

    Whenever you apply a changing voltage to a motor coil, the changing current will generate a changing magnetic field inside the coil which will induce a voltage.

    The polarity of this voltage is opposed to the voltage applied to the coil. Therefore it is called counter-electromotive Force or CEMF.

    In short:

    The counter electromotive force could generate voltage spikes. Phones don't like voltage spikes!

    We just wanted to show that it works with cheap DIY components and that the amplifier is not really necessary to make it work.

    To be on the safe side, you could use a flyback diode between power and ground, or use a piezo instead of a DC motor.