[MOD] Bone Conduction Mechanical Audio Amplification


Retired Senior Recognized Developer
Feb 18, 2011
Miami, Fl̨̞̲̟̦̀̈̃͛҃҅͟orida
As a Biomedical Electronics Tech, I have a great appreciation for human-machine interfaces. Interfaces must be tightly spec'd to the body or there is a loss of signal. One of the biggest complaints about Google Glass is the "crappy speaker". The speaker is not crappy, it's actually decent, it's just poorly positioned for just about everyone aside from Sergey Brin. If you have a larger than average head, you're out of luck because the Bone Conduction Driver sits on your Temple instead of your Mastoid (The hard bone behind your ear, used in Bone Conduction technology).

Well, you were out of luck... This mod can help you. After working on this for about a month, and much trial and error, I've come up with a near perfect hack for using Glass as a primary bluetooth headset and Pandora audio device. It sounds more like headphones and not a crappy cell-phone speaker sitting too far away. This modification can be undone easily, and should not affect your warranty.

Do I need this?
How do you tell if the bone conduction speaker is operating properly? Listen for the click. Simply wear your Glass and press on the portion behind the ear. If you hear a well defined click, Glass is properly positioned. If you do not hear a click, you should perform initial adjustment of the nose-pieces of glass in order to reposition the unit. They bend more than you think. If this does not work, then you should proceed with the following modification. In my case, the Bone Conduction Driver sits over my soft temple, instead of the Mastoid bone and that's a problem because I can't hear it. If you have the same issue, then continue on.

You will need
You will need the following in order to perform the modification.

Performing the modification
You may be able to figure most of it out by this picture, but here are some instructions.
  1. Place a V-shaped bend in the hobby wire. This is where the Lever will sit.
  2. Place the glasses temple on the hobby wire
  3. Using a pair of Pliers, twist the Hobby Wire to secure the temple to the thinnest portion of the Glass Body with the Lever extending past the end of Glass. Be careful not to twist too hard or the Hobby Wire will cause damage to Glass. From this point on, the lever is attached to Glass and should be handled carefuly
  4. Bend the Lever so it is flush with the Glass Bone Conduction Driver. It must be entirely flush with a bit of pressure applied.
  5. Place Glass on your head, and note where the Lever makes contact with your Mastoid.
  6. Cut the Lever using a pair of Diagonal Cutters (dykes), approximately 1/2 inch past the contact point of the mastoid-lever contact. Try to remove sharp corners.
  7. bend the end portion of the lever into a slight "C" shape, so as to remove contact with sharp corners. The C will be the Contact Surface for your Mastoid.
  8. Apply the Digitizer Tape to the lever, in the area where it will make contact with the Glass Bone Conduction Driver
  9. Before removing the Digitizer Tape Backing, ensure it sits flat against the driver with a slight amount of pressure applied to the end of the lever (simulating operating conditions)
  10. Remove the Digitizer Tape Backing and press the lever to the Bone Conduction Driver
  11. clip the Hobby Wire with the Diagonal Cutters so as to remove excess. You only need a ring of it.

Place glass on your head and press on the part behind the ear. If you've done everything correctly, you should hear an audible click when pressing and releasing.
IMPORTANT: Never pull to remove the Lever. Separate the lever from the speaker with a knife or needle, or other object. Pulling to remove the lever can cause the driver to separate from the coil. It can be glued back in place, but bad things can happen!

Just as Glass has its own adjustments to fit, this mod will also require adjustments. If things don't sound right, discontinue use and fix it with the following guide.

Sound isn't loud enough. You can move the lever closer to the back of Glass for higher amplification, or make the lever longer. But, there is a balance between pressure and amplification.
I hear pops in the audio. The pressure is too high, reduce pressure by bending the Contact "C" surface so it is closer to Glass.
Sound is muffled. If the lever isn't flush with the glass, then the driver can pop inwards.
I hear a click when I place glass on my head. There is too much pressure. Reduce pressure by bending the Contact "C" surface, so it is closer to Glass.
Certain high frequencies are causing a "ringing" sound. There is not enough tension on the fulcrum. the sound is caused by the Hobby Wire's movement. Tighten the Hobby Wire.

After this mod, the tones are richer, the bass can be heard and felt, the highs come across crisply, and the mechanical vibration gets amplified. This mod is everything Glass should have been, out the door. It's absolutely useful for calls, navigation, and Pandora after this. I hope this helps.

*AO stands for American Optics, not Adam Outler :D