Last November, thousands of unsuspecting New Yorkers heard a whisper: ‘Hey you, over here, don’t turn around… Do you ever think about murder?’ While a handful may hear voices on a regular basis, those new to the whispers were the targets of a state-of-the-art outdoor audio ad campaign employed by Court TV for its Murder by the Book series.

Dubbed ‘audio spotlighting,’ the system relies on a motion detector that beams a 30-second message to a very limited area where a customer is standing, reaching only the ears of the individual who tripped the device, without disturbing anyone else. Initially developed for the us military, this 30-day campaign is the first time the technology has been applied to advertising messages.

Court TV’s SVP of marketing, Mary Corigliano, says the initiative – as part of the cablenet’s one-on-one focused Come Hear marketing push – breaks through the bombardment of outdoor advertising by surprising its target. By taking them off guard, respondents are more likely to stick around and listen to the message. And since the series delves into the thought processes of top mystery writers, it’s a no-brainer to have those authors voice promos that speak directly into the ear of the viewer.

Zoom Media was employed by the cablenet’s agency, New York’s Mediastorm, to scope out destinations to reach its 35- to 54-year-old, mystery book-loving target. Patrick West, VP of experimental marketing at Zoom in New York, says the challenge was to marry the audio spots with the appropriate setting, and then convince the businesses that this audio spotlighting would not interfere with its operations. Mystery bookstores and cafés conducive to quiet reading were chosen as top destinations, but there was some resistance when approaching business owners. ‘When you approach a bookstore and tell them you want to put in a special speaker that’s motion activated and whispers in people’s ears about murder, the majority of the reactions are ‘Oh no you’re not,” says West.

In total, 11 locations in Manhattan and a few spots in Atlanta (the home of Court TV’s parentco) were installed with the technology, and although Mediastorm’s director of media and marketing strategy Marc Klatzko says Court TV didn’t track its reach, West says one of the motion detectors used in a trial run was clocking in about 1,000 trips in an average day. To make sure the campaign ran smoothly, Zoom kept in regular touch with the location managers, who would be the first to express concern if the Mystery Whisperer was turning away shoppers.

A local TV station also received mostly positive man on the street interviews about the campaign, although some in the older demos found it invasive. West says even though some of those outside the core demo may have found it frustrating, ‘it’s better to whisper to 1,000 who might be your ideal audience than yell to a million who wouldn’t care or would find it intrusive.’

The series is attracting an average of 503,000 A18-49 (27% increase versus the same time period in 2005) and an average of 555,000 A25-54 (32% increase versus the same time period in 2005) since its debut in mid-November. While that’s high for the cablenet, Corigliano couldn’t say if she’d use the technology again, if only because it might become too popular.