Bone conduction speakers for radios have been around since World War II. But building them so they were rugged and reliable enough for combat has been more difficult. A French firm (Elno) apparently has solved the problem, as they have a contract to supply OH 395 full bone conduction headset for the new personal radio being issued to French troops. The Elno device speakers rest on the skin just in front of the ear, and transmit the sound, via bones there, to produce a very clear sound. You can still hear through your ears, which is an important issue for combat troops.