Ordinary speakers emit sound in all directions, to achieve directionality, the diameter of the speaker must be made very large. Different from the principle of traditional speakers, active directional speakers first low-frequency sound signals contained in a highly directional high-frequency signals on top, and then amplified, launched into the air, and then the air will be the high-frequency signals quickly filtered out the audible sound signals on it will naturally filtered out, to achieve the directional propagation of the laser like.
Active directional speakers are able to control sound waves in a specific area, in which the sound waves are very strong, and out of this area, the sound waves will be very weak, or even none. If square dancers use this kind of speaker to play music, its nuisance 'embarrassment' can be solved."