KDDI is showing off a prototype of its speaker-free Android phone at CEATEC in Japan this week. As reported by Ubergizmo, the device uses bone conduction to transmit sound through the bones of the skull to the eardrum. Without a speaker, it is much easier to make a phone water-resistant, and — theoretically, at least — this phone would work better in noisy environments, even if the author noted that this was definitely not the case on the show floor this time around. No word on when the technology will be ready for primetime, or how much such a handset might cost, but soon as it is viable we're sure we'll start seeing it in a whole host of bright yellow, ruggedized handsets.