TECHNOLOGY used by the American military to fool their Iraqi enemies into hearing sounds of things that were not really happening is now on sale in Bermuda.

Entrepreneur Raynard Smith, of Filter Queen Bermuda, is offering "hypersonic sound" systems that can generate a narrow beam of sound that can be heard only by someone directly in its path.

Mr. Smith has one of the speakers rigged up in his Dundonald Street premises and can demonstrate its remarkable capabilities to customers.

Stand in the line with the speaker and the sound of birdsong or running water being played off a compact disc can be heard clearly. It is as if the sound is coming from inside the head.

Step aside a couple of feet, outside the width of the invisible beam and you can hear virtually nothing.

Ultrasonic technology makes it possible to generate a beam of sound that is like a spotlight and that can be bounced off surfaces like light off a mirror.

The US Army used hypersonic sound to fake troop movements in Iraq.

"It can send a strong signal over a distance of 150 yards and you can pinpoint exactly where you want the sound to go," Mr. Smith said.

"This technology has all sorts of potential applications. You could use it in a car showroom, so that if someone stands and looks at a car they hear characteristics of that car. It would be like the car itself was speaking.

"You could have a beam of sound being directed down from the ceiling in a jewellery store, so that when someone stood in front of the cabinet below they could get a commentary on what is in the cabinet."

The technology could also be used to play a narration relating to a specific display that could be heard only by someone standing near that display.

And at sports events or in crowd control, officials could use a portable hypersonic loudspeaker and get a message to whomever they targeted with it.

There are also numerous domestic possibilities which will come as good news to people who like to read in peace in a room where someone else wants to watch television or listen to a stereo.

"If the speaker is directed at the person watching TV, then no-one else will be able to hear it," Mr. Smith said.

When Mr. Smith first received one of the devices he set up the speaker outside his store and aimed it across Dundonald Street.

He said it mystified several passers-by who were visibly agitated and confused when they were caught in the beam and suddenly heard a mysterious and crystal clear sound seemingly coming from inside their head.

The science of hypersonic sound is complex. In simple terms, it depends on an ultrasonic (beyond the range of human hearing) sound wave being sent into the air.

When that wave is sent at sufficient volume, the air it comes into contact with causes the air create new frequencies, which can be heard by those within the ultrasonic beam.

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