Motorola recently introduced the Endeavor HX1 Headset. This hands free device is bluetooth enabled, and features Motorola's CrystalTalk technology along with the new Stealth Technology. The Stealth Technology uses bone conduction (not a microphone) to relay only your voice. This eliminates any background noise, no matter how loud. Pretty remarkable technology. I put it to the test on a few outdoor adventures. Below you can listen to recordings I took of phone calls in Stealth Mode.