You got this thing wedged in your ear because otherwise you can't hear what the damn whippersnappers are all yappin' about. Then along comes this other earpiece you're supposed to jam in your ear, so that you can talk on your cellphone while driving or juggling or whatever the kids are doing these days. Along comes some German designer who says, why not use the same contraption for both purposes? Figures.
It's so obvious, I wonder why Jawbone or Plantronics didn't think of it first. (Maybe they have—readers?) The trouble is probably execution. This prototype was created for an actual hearing-aid manufacturer, but the functional details are scant and in German. All Babel Fish could say is, "In this innovative hearing aid with navigational auxiliary functions applied it falls thus, one on older humans cut handling to develop user guidance and product diagram." Maybe your Deutsche is better.