Hearing voices in one's head may precede a trip to a neurologist. But not necessarily, if you're riding a train equipped with Sky Go. German ad agency BBDO Deutschland has teamed up with Sky Go to produce a new kind of advertising that beams messages to a person's head as they ride on a train.

Huh?

It works using a small box-like device called a Sky Go module, which delivers audio advertisements in the form of vibrations across the train's windows. When a commuter leans her head against the window, the vibrations get transmitted to her skull and through the bones in her ear in a way that allows her to hear the message.

The technique relies on a known phenomenon called bone conduction, which is a way to deliver sound directly to the inner ear, bypassing the ear canal and middle ear. The concept isn't new. Specialized headphones, hearing aids and some military communications equipment use the technique because it cuts out ambient noise without making the sound louder, which can damage ears. In addition, ads delivered through vibrations in the windows won't disturb other commuters on the trains, who won't hear the ads if they're not leaning their heads against the glass.

BBDO told the BBC that it is working on the concept for Sky Deutschland, a satellite TV company.

While company spokespeople said the idea got good feedback from customers - they told news outlets that BBDO initially used it for weather reports - the feedback in the comment sections on the YouTube demonstration video has been less than enthusiastic. "The worst invasion of privacy since the cell phone," one said and, "The only thing I would lay on that window is metal bat..." are typical. Another was, "Excellent way to reduce overcrowding on trains! I'll take the bus." Some commenter suggested a simple way around it: bring a piece of soft material that would go between the sound generator and the window.

For the record, Sky Deutschland said it hasn't made any decisions about whether to adopt the technology.

Source: BBC, Gizmodo Australia