After more than a decade of development, technology that directs a beam of sound straight into a person's eardrums is ready for prime time.
The new technology has attracted some attention from critics who worry it gives advertisers far too much power to invade a consumer's privacy when promoting their products where shoppers congregate.
Hypersonic technology aims to eventually make blaring loudspeakers and broadcast marketing messages obsolete in stores and malls.
In December, the A&E Television Network used the technology on a busy downtown Manhattan street to promote its show Paranormal State. The new program is about ghost hunters who investigate haunted locations, and people walking by an advertisement heard voices whispering, "Who's there? What's that? It's not your imagination."
The technology works by beaming waves of hypersonic sound at a pitch that is undetectable by the human ear. The waves continue until they smash into an object such as a person's body. The waves then slow, mix and re-create the original audio broadcast. If the person steps out of the waves, they are no longer obstructed and they are rendered inaudible.
The promotion was an enormous success. New Yorkers heard about the freaky advertisement and flocked to its location to experience it first-hand.
"The technology really basically made it seem like the sounds were coming from inside your head," said Lori Peterzell, vice-president of marketing for A&E. "It was totally a freak-with-your-mind experience."
Using the technology, marketers can target an audio message at one person in a crowd of hundreds, leaving everyone around that person unaware.
"This prevents the noise, it doesn't add to it," said Joseph Pompei, founder of Holosonic Research Labs, Inc., which is in the hypersonic sound business.
The technology is in use at the New York City Public Library, where a giant wall of TVs broadcasts news for people to watch. People hear the broadcast if they stand in front of the TV, while those wandering through the library's aisles hear nothing.
