How to assess the noise reduction efficiency of road noise protection screens?

How to assess the noise reduction efficiency of road noise protection screens? cid=6

Noise screens of different shapes are often seen on motorways or on the sides of roads. These screens are installed to reduce noise generated by transport, but how effective are they and how are they measured?

In fact, the effectiveness of noise shields can be assessed in the following ways:

On-site measurements: on-site measurements allow the determination of noise levels before and after installation of noise shields and the calculation of noise reduction. This requires the use of professional noise meters or other measuring equipment and the measurement of sensitive points such as residential areas or schools.

Sound insulation level: this is a key parameter for measuring the performance of sound shields, usually expressed in decibels (db). The sound insulation level indicates the extent to which the noise shield reduces noise. For example, if the sound insulation level of the noise shield is 20 db, it means that the noise level behind the screen is 20 decibel lower than in front of it.

Sound absorption coefficient: also known as sound absorption coefficient, this parameter shows the ability of the sound protection screen to absorb noise. The higher the sound absorption coefficient, the more noise the screen absorbs. This parameter depends on the material, surface treatment and noise screen structure.

Noise suppression coefficient (NRC): this coefficient assesses the sound absorption of noise shields, usually in the frequency range of 100 hz to 5,000 hz. NRC is an average of sound absorption factors at four frequencies: 250 hz, 500 hz, 1000 hz and 2000 hz, and is used as a single indicator of the sound absorption properties of the material.

Reflection factor: the reflection factor shows the ability of the noise shield to reflect sound. If the reflective coefficient is high, the sound can create an echo behind the screen, which reduces its efficiency. Therefore, it is important to avoid high reflection factors when designing and selecting noise shields.

Spectrum analysis: noise analysis on a private spectrum allows to determine the effectiveness of the noise protection screen in reducing noise at different frequencies. This helps to understand the noise shield in different applications.

The effectiveness of noise shields can depend on many factors, including the characteristics of the noise source, environmental conditions, and the quality of screen design and installation. In addition to the acoustic indicators mentioned above, the appearance, design, installation and durability of the noise shield should also be taken into account. When selecting and using noise shields, it is important to consider all these factors in an integrated manner in order to achieve optimal noise reduction.