Its technical principle is actually the use of ultrasound directional properties. Such equipment is currently used in many areas, such as square dancing, before always seen in the newspaper "square dance magic weapon" "square dance forced to stop the device" and so on, are active directional speakers. In addition to outdoor plaza, in the outdoor large screen advertising, advertising machines, shopping malls and supermarkets, museums and expositions have a very wide range of applications.
At present, active directional speakers have been commercially available abroad, but there are not many domestic manufacturers who can realize it.