High technology, of course, is a slow-turning ship, and some trade heavyweights believe that HSS, while interesting, has real limits. Floyd Toole, a vice president of acoustical engineering at Harman International -- the $1.8 billion corporation that owns JBL and Infinity -- is skeptical. ''HyperSonic Sound is not going to revolutionize the world, not going to replace the loudspeakers that we've all grown to love,'' Toole says. ''I was once quoted, incompletely, as saying HSS is 'a great party trick' -- and it still is! Actually, it's also a very useful device. In basic communication, its applications are limited only by the imagination. Though, the last time I saw it, three months ago, it still had a lot of distortion. It had no low range. You wouldn't want to enjoy music using HSS, but it can really hit a target. Still, we're not threatened. Nor is Woody trying to take our domain.''

Woody is not. His strategy is to avoid confronting major speaker firms -- for the time being. Better to start small, to look for places that currently don't have much to do with the acoustics trade. Museums, soda machines, produce aisles. ''We're gonna go after the low-hanging fruit, places where you don't yet find sound, so HSS will not be regarded as a threat,'' he says, before showing some of the flick-knife steel that had to be buried in there somewhere. ''And when we get strong, that's when we hit with a vengeance. We'll license with some Goliath of the industry -- a Sony or a Philips. Know how many new speakers were installed in 2002, from buses to boomboxes? Fifteen billion units. In'nat cool?''

Not surprisingly, people who've heard of HSS have responded variously. On any given day, Norris might receive 17 e-mail messages from a company in Hong Kong begging to manufacture HSS -- and several from civilians who think he's either a genius or a psychopath. One man recently wrote to insist that Norris ''be jailed'' if he fields this product (curiously, sending this demand to Norris). And a woman wants to secretly install HSS in her lover's car or golf bag so that she may continually transmit a message deep into his head: Marry Donna. . . . Marry Donna.

Let some rave and others rage. It's all cool. Woody Norris is at his ease. He made his fortune 35 years ago and is now wealthy beyond his own ability to measure. His first invention was a medical product, simply because he was approached by a few friends who wanted to form a company but had nothing to sell -- and the man with the most money to invest was a doctor. So Norris went and bought a flashlight at Radio Shack (evidently his spiritual home), then picked up a piezoelectric crystal and fine-tuned his knowledge of the Doppler effect until he puzzled out a way to detect clots in blood vessels. This entire process took a Friday night and most of a Saturday. ''It was called 'Transcutaneous Doppler,' '' he recalls wistfully -- before adding, as a throwaway, ''Eventually, it evolved into the sonogram.''

There were a score of other inventions. Some panned out; some didn't. American Technology Corporation came into being in 1980 to nurture a long-play tape recorder, one that could fit 20 hours of sound on a regular cassette. Of course, CD technology put an end to all that. Shame, too, Norris says. They'd worked with drama students and everything -- had the whole New Testament recorded on one tape.

Despite his claim that he is ''a fundamentally lazy man,'' Norris was always tinkering. There was his innovation of the digital recorder in 1994 (another Popular Science ''Best of'' pick); the world's tiniest FM radio, weighing less than one-quarter of an ounce; a tracking device for wayward toddlers. These days, Norris's new love is the AirScooter, a personal helicopter that takes no more than an afternoon to master. It's slow, smooth and lacks the complexities of an actual copter. And, as it has been whittled down to meet the government's ''ultralight'' standard -- weighing less than 254 pounds -- you need not be licensed to fly it.

Often, Norris says, inventions are the result of some left-field theory he blurts out before he has time to think it through. Scientists at NASA once got wind of an offhand remark he had made about wireless receivers and flew him to Texas; they'd been having trouble with boom microphones slipping around inside space helmets. ''Suddenly I hear these words coming out of my mouth,'' Norris recalls: '' 'Well, I can give you a one-piece system so you won't need a boom mike at all. The sound can come through the bones in your head!' And the NASA guys were, like, 'Yeah. Right.' '' Thirty days later, Norris had a prototype, which the space agency grabbed with both hands. Norris translated the concept into an ''all-in-your-ear headset'' that came to be called Jabra.