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hypersonic sound
Jul. 23rd, 2003 05:49 pmIt's a new way of projecting sound that allows the same kind of private listening headphones offer, without any of the cords or hardware.
Woody Norris is the inventor of hypersonic sound, a novel technology which uses vibrations that occur outside the range of human hearing:
"It's generally defined that the range of hearing extends from - on the low end, down to twenty cycles per second - all the way up to twenty thousand cycles, or vibrations, per second. When you go above that, it's still mechanical vibration of air molecules bumping into each other. And the air is actually capable of vibrating many millions of times a second, believe it or not."
While air can vibrate at high speeds, our ears can't detect these very high frequency sounds. Hypersonic speakers -- or emitters -- capitalize on this. They produce different streams of high frequency sound starting at one hundred thousand cycles. That's well above the range of human hearing.
"You emit your hundred thousand, and hundred one thousand cycle signals into the air, and by some magic which happens in the air itself, the difference between those two tones is made right in the air. In fact, it's made all along an infinite number of points in that ultrasonic column. In this case, the difference is a thousand cycles, which people can hear."
By creating two streams of high frequency vibrations, an audible sound can be produced and it can be pinpointed and transmitted up to a hundred fifty feet away.
"For instance, if you're a lifeguard or a policeman trying to have riot control to get the instigator of a riot, you can point it at a lead person and communicate with that person. We've got people in Florida and in New York using it to scare away birds."
Voices of Innovation is presented by the American Association of Engineering Societies.
Woody Norris is the inventor of hypersonic sound, a novel technology which uses vibrations that occur outside the range of human hearing:
"It's generally defined that the range of hearing extends from - on the low end, down to twenty cycles per second - all the way up to twenty thousand cycles, or vibrations, per second. When you go above that, it's still mechanical vibration of air molecules bumping into each other. And the air is actually capable of vibrating many millions of times a second, believe it or not."
While air can vibrate at high speeds, our ears can't detect these very high frequency sounds. Hypersonic speakers -- or emitters -- capitalize on this. They produce different streams of high frequency sound starting at one hundred thousand cycles. That's well above the range of human hearing.
"You emit your hundred thousand, and hundred one thousand cycle signals into the air, and by some magic which happens in the air itself, the difference between those two tones is made right in the air. In fact, it's made all along an infinite number of points in that ultrasonic column. In this case, the difference is a thousand cycles, which people can hear."
By creating two streams of high frequency vibrations, an audible sound can be produced and it can be pinpointed and transmitted up to a hundred fifty feet away.
"For instance, if you're a lifeguard or a policeman trying to have riot control to get the instigator of a riot, you can point it at a lead person and communicate with that person. We've got people in Florida and in New York using it to scare away birds."
Voices of Innovation is presented by the American Association of Engineering Societies.
