Comparing with general speaker which spread to all directions,
Ultra Sonic Wave Speaker send sound to the designated direction only like flashlight.
Thank to this unique character, it can be used many area.
Sound has directivity as frequency increases.
In case of general speaker, wooper (20Hz ~ 150Hz) has almost no directivit
and tweeter(5kHz ~ 15kHz) has a little directivity.
Ultra Sonic Speaker radiates audio signal with on Ultra Sonic wave range(20kHz ~ 80kHz) to make directivity as light, air make audio signal within ultrasonic wave direction and radiates at designated area like flaslight.