How does Ultra Directional Speaker Work?

Ultrasound directional speakers work in a completely different way than traditional speakers. The main difference is that they don't generate ordinary audible sound waves through a single moving solenoid and cone. Ultrasound directional speakers are used because the higher frequency waves of ultrasound have correspondingly shorter wavelengths and spread less as they travel, and they stay in the beam longer than normal sound.

The ultrasonic waves then travel out of the ultrasound directional speakers in the form of a narrow-focused column, like a flashlight beam. An ultrasonic speaker array actually produces a modulated wave consisting of two separate ultrasonic waves. If they hit an obstacle, they suddenly slow down and mix, creating a third wave, the frequency range our ears can hear. Directional ultrasonic speaker transmits sound in a more tightly concentrated array, consuming much less energy. When no one is standing in the covered sound beam, the sound waves continue to propagate without producing audible sound waves - so if no one is standing in front of the ultrasonic directional speaker, we cannot hear it clearly. People standing outside the sound beam almost can't hear sound because (unlike traditional speakers) the sound waves don't radiate from the sound source to their ears.