I frequently visit Kickstarter screening for interesting ideas.
One of them caught my attention: Hushme promises privacy when speaking on the phone in meetings and public places.
In the passive voice muffling mode, Hushme is locked over the mouth using magnetic coupling. This mode is provided by the innovative insulation materials, that are embedded inside the mask, by the extra soft cushion muffs and by the special sound-absorbing paint, that covers the whole inner surface of the device. So, people at the distance of 3 feet cannot decipher your words, while your speech is transmitted to the other end undistorted thanks to sensitive built-in microphone.
Here is how Hushme works