WHAT MAKES A GOOD SOUND WALL
The most often asked question is are trees, vegetation and landscaping effective noise barriers? Although they help with aesthetics, they, unfortunately, do little to reduce noise.
Sound walls are classified as reflective or absorptive. Hard surfaces such as masonry or concrete are considered to be perfectly reflective. This means most of the noise is reflected back towards the noise source and beyond. A barrier wall with a surface material that is porous with many voids is said to be absorptive. This means little or no noise is reflected back towards the source.
Sound walls are performance rated in two categories Sound Transmission Class (STC) and Noise Reduction Coefficient (NRC). The STC determines the amount of noise energy transmitted through the wall material. The NRC determines the amount of energy absorbed by the wall material and the amount of energy reflected back towards the source.
Walls having STC ratings of 30 or more means that less than 0.1 percent of the noise energy is transmitted through the barrier material. Many State Department of Transportation specifications require minimum STC ratings of 24. Sound Fighter® LSE Walls have an STC rating of 33.
NRC measures the amount of sound energy absorbed and measures the amount of sound energy reflected back towards the source. NRC ratings will range between 0 (100% reflective) to 1 (100% absorptive). A wall with an NRC rating of .85 means the wall absorbs 85% of the noise and reflects 15% of the noise back towards the source. NRC ratings equal to or greater than .85 are considered to be good sound absorbers and are often used as the minimum requirement when considering absorptive walls. Sound Fighter® Wall Systems have an NRC rating of 1.05, making the wall 100% absorptive.
A good sound wall is a sound-absorbing wall with a STC rating of 30 or more and a minimum NRC rating of .85
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