This could be incredibly cool or amazingly irritating. The German arm of BBDO has developed a media channel based off technology normally used to aid the deaf in hearing. The small transmitter uses high-frequency vibrations to transmit ads through glass and into the heads of commuters resting on the train. The bone conducting messages can only be heard by individuals who have their heads pressed up against the window. We're not quite sure this is a positive thing, but it's extremely interesting.