Google Glass patent applications: bone conduction, laser projected keyboard, more

Bone conduction for covert audio. This would allow more privacy so that no one can overhear a conversation; a vibration transducer allows the technology to work without a direct connection. 
A laser projector can be used to project an interface on any nearby surface, including the user’s own hand.  The virtual input device includes a projector and a camera. The projector projects a pattern onto a surface. The camera captures images that can be interpreted by a processor to determine actions.
The projector may be mounted on an arm of a pair of eyeglasses and the camera may be mounted on an opposite arm of the eyeglasses. A pattern for a virtual input device can be projected onto a “display hand” of a user, and the camera may be able to detect when the user uses an opposite hand to select items of the virtual input device. In another example, the camera may detect when the display hand is moving and interpret display hand movements as inputs to the virtual input device, and/or realign the projection onto the moving display hand.