As we've heard before, Google's Glass project features are "still in flux" -- could one be a bone-conduction speaker? It very well may, at least according to a US patent application published today. The gadget, described as a "wearable computing device with indirect bone-conduction speaker," appears to be similar in structure to Glass. It includes "at least once vibration transducer," so it's possible that this HMD implementation wouldn't offer stereo sound. This audio solution does seem within reach -- Panasonic had functional bone-conduction headphones at CES, and while they weren't quite loud enough to provide an earbud-like experience, they did indeed work. As with any patent application, the document confirms only that Google was considering such a technology, not that it'll actually ship a similar device. So, if you've decided that your portable audio future will be headphone-free, you might want to keep an eye on Panasonic's solution, instead.