2004
RNC to Feature Unusual Forms of Sound
Unusual Forms of Sound to Emanate From RNC
Outside the convention hall, New York City police plan to control protesters using a device that directs sound for up to 1,500 feet in a spotlight-like beam. Meanwhile, a display of former Republican presidents inside the hall will feature campaign speeches that are funneled to listeners through highly focused audio beams.
"These are totally different from the way an ordinary speaker emits sound," said Elwood (Woody) Norris, founder and head of American Technology Corp. of San Diego. "It's like it's inside your head."
Norris, an intrepid entrepreneur who has no college degree but more than 43 patents to his name, invented both the crowd control tool, called the Long Range Acoustical Device (LRAD), and the display audio technology, called HyperSonic Sound (HSS).
Both technologies feature unprecedented manipulation of sound, but for very different purposes. And while both technologies have unique, "gee-whiz" factors, some remain uneasy with the idea of using sound to control crowds.
http://abcnews.go.com/Technology/story?id=99472LRAD -
The Long Range Acoustic Device™ (LRAD®) is a highly directional acoustic array that is designed for long-range communication and unmistakable warning. The LRAD device can issue a verbal warning and has the capability of following up with a deterrent tone to influence behavior or determine intent.
Conventional high output acoustic devices have semi-spherical propagation patterns making users and anyone located behind the unit subject to excessive Sound Pressure Levels (SPL). With large inductive loads, they consume high levels of power due to low efficiencies. They are heavy, bulky, and make it almost impossible to place sound exactly where you need it. Their reflections and secondary sounds cause lack of clarity, high distortion, and low intelligibility.
To achieve its unique directivity acoustic output, the LRAD utilizes highly efficient, customized capacitive transducers and requires modest power requirements- less than 200 to 400 watts to achieve full output. The high directivity of the LRAD device reduces the risk of exposing nearby personnel or peripheral bystanders to excessive audio levels. Sound behind the LRAD unit is over 40 dB less than the on-axis forward output. The LRAD also incorporates multiple highly efficient switch-mode power conversion systems. Its inherently compact and light nature makes operating the system easy.
For very high SPL's, low power consumption, long range, narrow beam, high intelligibility, and superior operator safety; the LRAD is the premiere choice.
http://www.atcsd.com/site/content/view/37/50/Bastards.