A woman rests her head against a train or bus window at the end of a long day. Suddenly, she hears a voice; it's talking to her. But no one else can hear a thing...

No, this is not the opening scene to a cheesy horror movie or science fiction thriller. This is German ad agency BBDO Düsseldorf's latest plan to reach consumers.

Using bone-conduction technology (yes, this is real), which emits an inaudible high-frequency vibration against the skull that the brain then translates into sound, advertisers may soon be able to put ideas into consumers' heads during their daily commute, Adweek reported this week.

This video demonstrates the technology in action.

The technique of bone-conduction is not a new one. Businessweek reports that hearing aids, water-proof earbuds and "safety" headphones for runners also utilize the technology. The technique has been favored by athletes because it does not block outside sound, and by the hearing-impaired because it can be used in conjunction with hearing protection.

Unfortunately, bone-conduction may present one major hurdle for advertisers. According to a study of the technology led by Justin MacDonald for the U.S. Army Research Laboratory, the tech can be subject to "crosstalk" between channels.

This effect is insignificant for localized waves like those contained in headphones, Mac Donald writes. However, it could become problematic on larger surfaces like train windows--particularly train windows emitting separate messages. Then there's the fact that it might just strike consumers as, well, creepy and invasive. 

But it may still be a while, both outlets report, before the tech is ready for this kind of use.