Why can directional sounds concentrate the sound in one direction?

According to the theory of acoustics, the frequency range of the human ear can be heard is 20HZ-20KHz. In the propagation process, the audible sound spreads in all directions, and the high-frequency sound waves with a frequency greater than 20KHz have good directivity in the transmission process. The higher the directivity is, that is, the ultrasonic wave (frequency band 20KHz-1GHz) has directional propagation characteristics.


What is the use of directional sound?

There are many scenes using directional audio. Currently, there are dozens of industries in LCD/LED media advertising, exhibition hall exhibitions, large-scale exhibitions, automobiles, education, and intelligent transportation. The following are some examples of scenarios:

The working principle of directional sound is: using a specific technology to modulate the audible sound to the ultrasonic frequency band, using the directional characteristics of the ultrasonic wave to achieve directional propagation. In layman's terms, an audible sound wave is mounted on an ultrasonic wave. Due to the directivity of the ultrasonic wave, the audible sound also has directivity, and at the same time, the ultrasonic wave can be naturally filtered by the human ear, leaving the audible sound to be heard by the human ear. This will achieve the broadcast function of audio transmission.