This prototype cellphone, from KDDI Labs and Kyocera, doesn't have a speaker. It doesn't need one. Put it up against your head and it sounds just like a regular phone with a speaker in it, and if you happen to be wearing industrial ear protection, it'll work perfectly straight through that, too.
The secret to this prototype speakerless cellphone isn't much of a secret: it's bone conduction. There's a tiny little chip in there (like 0.6mm tiny) that takes the audio coming through the phone, and instead of sending it to a speaker causes the entire back of the phone to vibrate. You can't feel it, but those vibrations transmit sound, and as long as that sound has some path into your head and to your eardrums, you can hear it just as if the sound was coming straight out of a speaker.
For this to work, the phone has to be in direct contact with you, so there's not going to be a speakerphone function or anything like that. It's well worth the compromise, though, since routing sound around your ears means that you can hear in situations where you would be otherwise unable to. For example, you can have headphones on and music cranked up, and you'll still be able to put this phone to your head and hear it. Or, you can be wearing the industrial ear protectors that the KDDI lady is modeling in the picture above, and pressing the phone to them (not even to your head) pipes sound all the way through.
This whole concept came about when a hard-of-hearing KDDI engineer got tired of using a hearing aid while on the phone, and whipped up a way to avoid the problem entirely. Kyocera liked it so much that they've decided to start producing this phone, and they'll be able to buy them in Japan his summer.
Posted on location at CES 2012 in Las Vegas. All photos by Evan Ackerman for DVICE.