A sound barrier is a sound barrier. In order to block the direct sound between the sound source and the receiver, it inserts a facility between the sound source and the receiver, so that there is a significant additional attenuation of the sound wave propagation, thus reducing the influence of the noise in a certain area of the receiver. Acoustic barriers are mainly used outdoors. Along with the road traffic noise pollution becomes more and more serious, some countries adopt various kinds of barriers to reduce the traffic noise. In a building, a barrier can also be used to separate the workshop from the office if sound insulation is not required. The barrier is more convenient to disassemble and move, and has certain sound insulation effect, so it is widely used.
The function of sound barrier is to prevent the transmission of direct sound, isolate the transmitted sound, and make the reflected sound have enough attenuation. Therefore, the attenuation of sound barrier is designed by using the principle of sound reflection. Sound waves (noise) for transmission on the way, if meet barriers (sound barriers), reflection will happen, so within the scope of a certain distance behind obstacles to form the “shadow”, the area size depends on the size of the voice (frequency), see from this, the noise attenuation of noise barrier is closely related with the center frequency value. Can be seen from the diagram, due to the high frequency sound shadow area is large, short wavelength, so the most easy to be blocked, the second is the intermediate frequency sound, the sound barrier formed behind the sound in the shadow of the low frequency sound, due to the long wavelength, circling around the barrier, it is easiest to diffraction in the past, so the surrounding environment will produce certain effect, so the noise barrier on its low-frequency noise sound insulation effect is poorer, proved by actual measurement: The sound barrier has no obvious attenuation for low-frequency sound with a frequency below 250Hz, but it has a better attenuation effect for medium and high-frequency sound.
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