Research on Noise Reduction Mechanism and Engineering Application of Sound Barriers

In modern urban environmental noise control, sound barriers serve as an effective passive noise reduction measure. Their noise reduction mechanism is mainly based on the principles of sound wave absorption, reflection, and diffraction. The noise reduction performance of sound barriers depends on multiple engineering factors, such as material properties, structural design, and installation parameters.

From an acoustic theory perspective, when sound waves encounter a sound barrier during propagation, three main physical phenomena occur: first, the reflection of sound waves, where some of the sound wave energy is reflected by the barrier surface; second, the diffraction effect of sound waves, where the sound waves continue to propagate around the edge of the barrier; and finally, the absorption and conversion of sound waves, where the sound wave energy is converted into heat energy by the barrier material and dissipated.

The acoustic performance of sound barrier materials mainly depends on parameters such as flow resistivity, porosity, and structural factor. High-quality sound-absorbing materials typically possess the following characteristics:

1. Porous structure: The material has an interconnected microporous structure with a pore size ranging from 10 to 500 μm.
2. Suitable flow resistance: Optimal sound absorption can be achieved when the material's flow resistance is in the range of 100-1000 Rayl.
3. Appropriate thickness: The thickness of the sound-absorbing material is related to the target noise reduction frequency, and is usually λ/4 (λ is the wavelength of the target frequency).

In engineering practice, the design of sound barriers needs to consider the following key parameters:

1. Insertion loss (IL): Typically 10-25 dB(A)
2. Sound barrier height: determined based on Fresnel number theory.
3. Surface structure: Employing textured surfaces or airfoil designs can improve noise reduction performance.
4. Material selection: Commonly used porous materials include glass wool and rock wool, with a sound absorption coefficient α > 0.8.

Taking a noise control project in an industrial park as an example, after installing a 4-meter-high sound barrier, the noise level at the factory boundary dropped from 75 dB(A) to 58 dB(A), demonstrating a significant noise reduction effect. Monitoring data shows that the sound barrier is particularly effective at reducing mid-to-high frequency noise (500-4000Hz), with a noise reduction of 15-20 dB.

The scientific application of sound barrier technology has not only improved the quality of the urban sound environment but also provided a reliable solution for the protection of the sound environment in noise-sensitive areas. With the continuous development of new materials and technologies, the application prospects of sound barriers in transportation, industry, and civil applications will be even broader.