Google has applied for a patent concerning a Project Glass-style
pair of glasses with built-in bone-conducting
headphones. The application
, titled "Wearable Computing Device with Indirect Bone-Conduction Speaker," would theoretically allow the wearer to hear audio played from the device privately without resorting to use earphones or external speakers.
The system would use "at least one vibration transducer" fitted in the frame, positioned in such a way that it would make a connection to the bone structure of the wearer, and so transfer audio vibrations to the ear. Engadget notes
that the system is unlikely to provide a stereo sound, and its mono audio nature would make it best suited to uses such as phone calls and audio-based notifications.
Alternative interfaces suitable for Project Glass has been explored during the device's development. One patent application describes how a finger ring
decorated with an infrared pattern could be used to control the head-mounted display, while a smartwatch
with a flip-up transparent display that mimics the Project Glass functionality has also been filed for with the USPTO.