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 direction.
Download the report: “Sound Walls: Absorptive versus reflective design and effectiveness”
The science is also simple:
A sound reductung 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. ¹
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.1
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. Reflective products like concrete or brick simply bounce sound waves in different directions. The LSE System actually “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 reducting 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 versus reflective. For many outdoor noise problems, well-engineered and efficient absorptive sound walls are fast becoming the noise mitigation tool of choice.
1 USDOT – Federal Highway Administration “Highway Traffic Noise” 6/05
Distinguishing Features of the LSE System Include