Why are Absorptive Noise Barriers better than Reflective Noise Barriers?
The answer is simple: Absorptive sound reflective materials eliminate sound waves that hit them. Reflective materials merely bounce them in a different directions.
A breakdown of the science behind absorptive and reflective materials:
A sound reducing barrier wall such as the LSE® 2000 with a porous surface material and sound-dampening content material is said to be absorptive. This means little or no noise is reflected back towards the source or elsewhere. Hard surfaces such as masonry or concrete are considered to be reflective. This means most of the noise is reflected back towards the noise source and beyond.
A noise barrier without any added absorptive treatment is by default reflective. In highway applications for example, a reflective noise barrier on one side of the roadway can result in some sound energy being reflected back across the roadway to receivers on the opposite side.
In this situation, it is a common phenomenon for one to perceive a difference in sound after a noise barrier is installed on the opposite side of a roadway. Individuals on the opposite side of the roadway may perceive a change in the quality of the sound; the signature of the reflected sound may differ from that of the source due to a change in frequency content upon reflection.
The Benefits of Absorptive Materials
While reflective products like concrete have been the traditional material for noise barrier walls and HVAC screens & enclosures, the advanced absorptive sound reflecting materials found in Sound Fighter® Systems’ LSE® Barrier Walls present a much more effective abatement option. Products like concrete or brick are reflective - they simply bounce sound waves off their surface in different directions. The LSE® System actually absorbs or “kills” the sound waves that hit it…significantly reducing overall noise.
It is also common to see parallel sound walls on roadways. Reflective parallel sound walls often reduce the wall’s acoustical performance. The net result is less than optimal performance and increased noise levels on and adjacent to the roadway
Absorptive parallel sound reducing walls reduce reflections and are able to maintain the effectiveness of the barrier. In addition, the overall noise level is reduced.
So which is the better sound wall design – absorptive or reflective? For many outdoor noise problems, well-engineered and efficient absorptive sound walls are fast becoming the noise mitigation tool of choice.
USDOT – Federal Highway Administration “Highway Traffic Noise” 6/05
Why LSE® Absorptive Noise Barrier System?
Sound barrier walls fall in one of two categories: reflective and absorptive. Let’s compare reflective and absorptive to get a better understanding.
Reflective Noise Barriers:
Barriers without any added absorptive treatment or design, such as block, concrete, wood or metal, are considered reflective. This means, in the case of highway applications for example, that sound energy actually bounces from one side of the roadway to the other. Because there are often reflective barriers on both sides of the road, reflective noise reverberates between the barriers and the vehicles, pouring out into the adjacent neighborhoods. This reflective phenomenon can actually increase overall noise levels to the affected residences.
Absorptive Sound Barriers:
Absorptive sound barriers, on the other hand, don’t reflect sound. In fact, installing a fully-absorptive barrier such as the Sound Fighter® LSE® system will eliminate the risk and problems of reflective noise altogether in any application.
Truly effective noise attenuation requires the use of sound-absorptive treatments, and no topical or textural treatments applied to reflective materials will ever compare to the sound absorption qualities of the Sound Fighter® LSE® Sound Barrier System. Used in a wide variety of applications ranging from highways and airports to loading docks and schools, the LSE® System is the ideal solution for virtually any outdoor noise mitigation requirement.
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