From: email@example.com (milne_v)
Subject: Coming soon to a theatre near you - endless mischief potential
Date: 12 Oct 2002 06:13:17 -0700
NNTP-Posting-Date: 12 Oct 2002 13:13:17 GMT
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
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.