Hi,
I recently build a pair of bone conduction headphones, and I want to share it with you. So lets start.
First of all, what is bone conduction??? Well, bone conduction is the conduction of sound to the inner ear through the bones of the skull. That means that the sound is not transmitted by air as normally a pair of standard headphones will do, this actually transmit sound through your skull allowing to listen music while you still hearing your surrounding. Cool, eh??
This headphones are capable of control the multimedia player basic functions and also have a built in microphone to allow take calls.
The solar panel will provide an extra power boost, is not too much but is enough to give 15 extra minutes of music and recharge the battery while the headphones are off. The lipo battery itself can power the headphones for around 50 minutes. And also you can provide external power via de mini usb connector, when you do this you can continue using the headphones while the battery is recharging. The battery status indicator only will be on while the battery is recharging over USB, in solar recharge mode the led remains off all the time to save energy. The bone conduction allow to listen your music while you still hearing your surroundings, so this headphones are nice when you are outside and you want to continue paying attention to the external world.
If you want to learn more and build your own, please see my instructable: http://www.instructables.com/id/Wireless-Bone-Conduction-Headset-headphones/
Thank you for reading my post! 
