Four Analogue Applicable Treatments For Directional Transmission Of Sound Waves.

1. Apply horns to enhance directivity
The second method is to add a horn in front of the speaker unit, especially in the middle and high frequency broadcast horns, professional speakers in the dance hall. The low frequencies of the horn speakers have not changed, but the directivity of the mid and high frequencies has been strengthened.
The medium and high frequency speakers can be controlled within 100 degrees vertically and in degree direction, and the attenuation can be more than 12dB outside the angle.
The interval between the two ends and sides from the throat to the horn exit is not equal, and the sound transmission is not equal (that is, the phase angle of the exit part is very different), so the wave front at the exit part tends to be a spherical wave centered on the throat. However, even if the speaker with horn is a spherical wave, the dispersion angle of the sound wave is much smaller than that of ordinary speakers.
2. Apply the sound hood to enhance the directivity
What kind of talent can concentrate the sound, perhaps in technical terms, enhance the directivity? One of the most complex and feasible methods is to use a polyacoustic hood, similar to a lampshade, only a large hemispherical cover is required on the tweeter, and the sound can be clearly heard by the person under the polyacoustic hood.
3. Use ultrasonic speakers to enhance directivity
The use of ultrasonic speakers to enhance directivity, the principle is to use the strong directivity of ultrasonic waves to complete the purpose of directional sound wave transmission. Ultrasonic waves are not prone to diffraction due to higher frequencies and shorter wavelengths, smaller pointing angles, and better directivity, while audible sound waves have lower frequencies and longer wavelengths, which are prone to diffraction and bypass the obstacles in the transmission process. Different from the principle of traditional speakers, ultrasonic speakers use ultrasonic waves as carrier signals, and then modulate the audio signal into high-frequency signals to complete directional transmission in the air, and finally complete self-demodulation in the air, so that the human ear can hear the restored audio signal.
4. Use "line arrays" to enhance directivity
In addition to the horn, another way is to let the speaker retract the cylinder wave, with multiple speaker units to stop the display, the broadcast column is easier to see cylindrical Boeing box, obviously, its vertical directivity is very strong, but the degree of directivity is ordinary. If you want to increase the degree of directivity, you can use "line array" speakers or columns, and display the speakers or columns in one row. An acoustic lens is added in front of these mid-woofers, the audio signal is digitized, the crossover and complex digital effects are stopped, and then converted to imitate signal discrimination to reduce the drive independently of each unit.