slightly scary but nevertheless interesting technology #2 of 2

[Richard LaFortune]

We've heard hypersonic sound. It could change
everything.

by Suzanne Kantra Kirschner





 It's the most promising audio advance in years, and
it's coming this fall: Hypersonic speakers, from
American Technology (headed by the irrepressible Woody
Norris, whose radical personal flying machine appeared
on our August cover), focus sound in a tight beam,
much like a laser focuses light. The technology was
first demonstrated to Popular Science five years ago
("Best of What's New," Dec. '97), but high levels of
distortion and low volume kept it in R&D labs. When it
rolls out in Coke machines and other products over the
next few months, audio quality will rival that of
compact discs.

The applications are many, from targeted advertising
to virtual rear-channel speakers. The key is
frequency: The ultrasonic speakers create sound at
more than 20,000 cycles per second, a rate high enough
to keep in a focused beam and beyond the range of
human hearing. As the waves disperse, properties of
the air cause them to break into three additional
frequencies, one of which you can hear. This sonic
frequency gets trapped within the other three, so it
stays within the ultrasonic cone to create directional
audio.

Step into the beam and you hear the sound as if it
were being generated inside your head. Reflect it off
a surface and it sounds like it originated there. At
30,000 cycles, the sound can travel 150 yards without
any distortion or loss of volume. Here's a look at a
few of the first applications.

1. Virtual Home Theater
How about 3.1-speaker Dolby Digital sound? With
hypersonic, you can eliminate the rear speakers in a
5.1 setup. Instead, you create virtual speakers on the
back wall.

2. Targeted Advertising
"Get $1 off your next purchase of Wheaties," you might
hear at the supermarket. Take a step to the right, and
a different voice hawks Crunch Berries.

3. Sound Bullets
Jack the sound level up to 145 decibels, or 50 times
the human threshold of pain, and an offshoot of
hypersonic sound technology becomes a nonlethal
weapon.

4. Moving Movie voices
For heightened realism, an array of directional
speakers could follow actors as they walk across the
silver screen, the sound shifting subtly as they turn
their heads.

5. Pointed Messages
"You're out too far," a lifeguard could yell into his
hypersonic megaphone, disturbing none of the bathing
beauties nearby.

6. Discreet Speakerphone
With its adjustable reach, a hypersonic speakerphone
wouldn't disturb your cube neighbors.

http://www.prisonplanet.com/audios_the_next_big_thing.html



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