AnandTech: CES 2006 - Day 2: Blu-ray/HD-DVD, PureVideo H.264, Viiv, Centrino Duo and a lot more: "Motorola In-Ear Bluetooth Headset
Motorola showed off a very cool design for their latest Bluetooth headset. Aside from being extremely small, the H5MINIBLUE is unique because the microphone resides in your ear canal. It listens to your voice by sensing the vibrations of your speech through your jaw.
This may seem odd at first; however the benefit of this design is that the listener on the other end of the call will hear almost no background noise from the user’s environment. So if you’re in a crowded convention center trying to talk on the phone, you don’t have to worry about the person you’re calling having to hear all the other conversations going on around you as well. At the same time, you don't have to yell to be heard on the other end of the conversation."