Research on the noise reduction mechanism of sound barriers and their engineering applications

In modern urban noise management, sound barriers are an effective passive noise reduction measure. Their noise reduction mechanism is primarily based on the absorption, reflection, and diffraction of sound waves. The noise reduction performance of sound barriers depends on multiple engineering factors, including material properties, structural design, and installation parameters.

From the perspective of acoustic theory, three main physical phenomena will occur when sound waves encounter a sound barrier during propagation: first, there is the reflection effect of sound waves, where part of the sound wave energy is reflected by the surface of the barrier; second, there is the diffraction effect of sound waves, where the sound waves will bypass the edge of the barrier and continue to propagate; finally, there is 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 structure factor. High-quality sound-absorbing materials usually have the following characteristics:

1. Porous structure: The material has interconnected microporous structures with pore sizes ranging from 10-500μm
2. Suitable flow resistance: The material flow resistance is in the range of 100-1000 Rayl to achieve the best sound absorption effect
3. Appropriate thickness: The thickness of the sound-absorbing material is related to the target noise reduction frequency, usually λ/4 (λ is the wavelength of the target frequency)

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

1. Insertion loss (IL): typically up to 10-25dB(A)
2. Sound barrier height: calculated based on Fresnel number theory
3. Surface structure: Using concave and convex surface or airfoil design can improve the noise reduction effect
4. Material selection: Commonly used porous materials such as glass wool and rock wool, with sound absorption coefficient α>0.8

For example, in a noise control project at an industrial zone, the installation of a 4m-high sound barrier significantly reduced noise levels at the factory boundary from 75dB(A) to 58dB(A). Monitoring data shows that the sound barrier is particularly effective at reducing mid- and high-frequency noise (500-4000Hz), with a reduction of 15-20dB.

The scientific application of sound barrier technology not only improves the quality of urban acoustic environments but also provides a reliable solution for protecting the acoustic environment in noise-sensitive areas. With the continuous development of new materials and technologies, the application prospects of sound barriers in transportation, industry, civil engineering, and other fields will be even broader.