Kyocera isn’t really known for successful innovation in the smartphone realm. Anyone that remembers the dual-screen monstrosity that was the Kyocera Echo can attest to that. With Kyocera’s newest foray into Android smartphones, however, there is a notable feature that you don’t see much of. The Kyocera Urbano Progresso uses the bones in your head instead of a speaker to deliver sound to your ear. It’s called bone conduction, but how the heck is it supposed to work?

The sound you go around hearing all day is obviously transmitted to you through the air by sound waves, but you also experience bone conduction. When you speak, your own voice is transmitted through the skull as vibrations. Since bone is considerably more dense than air, your voice sounds lower to you. Ever hear a recording of your own voice? It probably sounds higher than you hear it in your head. Electronic gizmos that use bone conduction need to account for the frequency shift to avoid distortion.

A device that uses bone conduction audio is essentially bypassing the ear drum. It is your eardrum (or tympanic membrane) in the middle ear that concentrates sound waves down into vibrations that can be detected by the cochlea in the inner ear. Bone conduction vibration waves simply affect the inner ear directly. To think of it another way: a bone conduction transducer can act as your eardrum.

A major problem with bone conduction has always been the quality of the sound. Because of the nature of the bones making up your skull, stereo sound is muddy and harder to keep straight. With a phone outputting only mono sound, this is no problem. The range of frequencies you can pick up with bone conduction audio is also narrower than with sound through the air. Again, this is much more a problem for music than it is for phone calls which already have fairly poor audio quality.

One of the biggest barriers to getting bone conduction technology in phones has been the power requirement. It usually takes more power to output enough energy in the form of vibrations to match the volume you would get over the air. Kyocera claims to have solved this problem with its proprietary Smart Sonic technology.

So in a phone, the disadvantages of bone conduction are minimized, but there are also a few clear advantages. If you’ve ever been in a noisy room trying to take a call, you know how frustrating it can be as you press the speaker harder and harder to your ear in hopes of blocking out some of the background noise. With bone conduction, the sound passes right from the transducer to your inner ear making it easier to hear the other party.

People that are hard of hearing could also find unique benefits in the kind of bone conduction used in the Urbano Progresso. Most cases of hearing loss come from damage to the eardrum, which bone conduction handily circumvents. Some users with hearing loss already use hearing aids that make use of bone conduction, so the technology in this phone is not without precedent.

Kyocera plans to bring its Smart Sonic transducer technology to the US next year, but the Urbano Progresso is launching soon on Japanese carrier KDDI. Reportedly, the sound on the Kyocera Urbano Progresso is quite good, so perhaps this will be the first smartphone to successfully get this technology into people’s hands — and ears.