Monday, 12 January 2009

Hypersonic sound speaker (HSS speakers)

The principle underlying HSS technology was first described by 18th century Italian composer, Tartini, who found that if one plays two different tones loudly at the same time, a third tone is produced which has a frequency that is the exact difference of the frequencies of the other two.

HSS systems apply the 'Tartini principle' electronically and use ultrasonic sounds that are beyond the range of human or animal hearing. HSS sounds are actually a combination of two sound waves: a 'carrier' wave with a frequency of 200,000-hz, and a second wave in the 200,020 to 220,000 hz range. Subtract the latter from the former and you get sound in the 20 to 20,000 hz range - which is the actual audal range of human beings: deep bass notes (20-hz) to shrill, 'high notes' at 20,000-hz.

The sound waves emitted by HSS systems are tightly focused. Since they are at a range that is not audible to humans, they are not heard until the waves encounter an obstacle - a wall, vase, door, or person. At this point, the carrier wave 'drops out' and only the audal sound is heard.

The technology is winning believers from Wal-Mart to McDonald's, Fox television, the Los Angeles Police Department, Procter & Gamble, the U.S. Navy and Cirque de Soleil. It is looking into whether HSS could be used to communicate instructions, midact, from the ground to a trapeze artist without the audience hearing. Companies are experimenting with HSS in TVs, rock concerts, museums, war and airport gates. Imagine hearing only your flight's announcements. In 2002, Popular Science magazine awarded HSS the grand prize for inventions. The Segway personal transporter took second.

"It offers huge benefits over your standard speaker systems," says Sony executive Simon Beesley, who is working on HSS in commercial settings, such as stores or restaurants. "The technology is in its infancy, but I am sure it will very quickly expand."

As it does, HSS will probably rattle the speaker industry, which has been selling a variation of the same technology for nearly 80 years. The impact could be like that of the jet engine on propeller planes or the PC on the mainframe — a major shift that ushers in an era.

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