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Have you ever been indiscriminately disturbed by square dance music or campus announcements? Have you ever imagined that sound could be directed like a flashlight beam? Breakthroughs in acoustics are making this vision a reality. How does this "sound sniping" work? And how will it reshape our lives?
The "laser pointer" of sound: The principle of directional sound generation revealed
Unlike the "splashing" diffusion of traditional speakers, directional sound technology propagates sound waves in a straight line. The core technologies are divided into two categories:
1. Ultrasonic carrier technology
By utilizing the high directivity and nonlinear effect of ultrasound, the audible sound signal is modulated onto the ultrasonic carrier and transmitted directionally through the transducer array.
2. Beamforming technology
Based on array signal processing, the sound waves of multiple groups of speakers are delayed and weighted so that they are superimposed in space to form a directional sound beam.
This technology, which originated from military sonar, is becoming a new weapon to solve noise pollution:
Public Space: Confine square dance music to the dance floor, restoring tranquility to surrounding residential areas
Educational scenario: Playground broadcasting no longer interferes with teaching buildings, achieving "joyful activities in active areas and tranquility in quiet areas"
Traffic management: Highway warning sounds are transmitted directly to the driver's seat to avoid interference from ambient noise.
Cultural exhibitions: Each exhibit has its own independent commentary, eliminating the reverberation of the exhibition hall.
The extension of military technology: the "invisible blade" of directional sound waves
LRAD long-range acoustic device: It can emit 145 decibel focused acoustic waves (equivalent to the noise of a jet taking off) from 2,500 meters away, forming a "sonic wall" only in a specific direction
Acoustic sniper system: Through millimeter-level sound wave reflection, it can identify heartbeat characteristics in the dark from 50 meters away.
Directed communication: Achieving secret communication within 500 meters that only the target can hear during special operations
Inspiration from nature: Masters of biodirectional acoustics
Such technologies have long been pioneered in nature:
Bats: emit narrow-angle ultrasonic beams of 15-20 degrees (close to the accuracy of military sonar) and can detect obstacles as thin as 0.05mm.
Toothed whales (such as dolphins): switch between 200kHz positioning waves and 20kHz communication waves through the "melon organ" in the forehead
Reshaping the Urban Soundscape: From Noise Reduction to Sound Rights
Directional sound products from companies like Sanyuan Environmental are driving the adoption of this technology. When pedestrians enter a specific area, the device automatically triggers customized sound effects, allowing for simultaneous playback of independent content in different zones. This intelligent soundscape management offers innovative solutions to chronic urban issues such as square dancing noise.
Noise pollution is a chronic problem in modern cities. The World Health Organization states that long-term exposure to noise levels above 55 decibels significantly increases the risk of cardiovascular disease. The revolutionary nature of directional sound technology lies not only in reducing noise but also in reshaping the spatial ownership of sound-allowing sound to be heard clearly where it is needed, while protecting quiet areas from disturbance.
Technological Revelation:
As sound transforms from a disorderly intruder into a precisely controllable urban element, we are witnessing the evolution of an acoustic civilization. Empowered by technology, public spaces will achieve the ideal of "lively where loud, and silent where quiet."