What are Sound Barriers and Noise Walls?
Sound barriers and noise walls effectively cut down on noise pollution within or outside of a residential or commercial building. They are designed to be retrofitted to existing walls or can be used as new construction. Noise barriers are made out of several varieties of material, each with different levels of efficiency. There are several ways engineers that incorporate noise-mitigating strategies into building design. Soundproofing materials are made to either absorb or reflect sound energy to the benefit of the type of environment desired.
Noise pollution poses moderate health risks at certain levels. Levels over 65dB are considered “naturally unacceptable” and can lead to an increase in blood pressure, stress related illnesses, tinnitus, and even hearing loss. In communities where residential buildings and businesses are exposed to 65dB or more, noise mitigation strategies are highly encouraged. New construction that impacts the surrounding environment, over 75dB, is required to have a noise control plan.
The main concepts when designing sound barriers and noise walls are to block, redirect or to absorb the sound. Increasing the distance sound travels is effective as the sound waves lose both energy and density. A “reflective” solid barrier can be used to redirect the energy away from an area impacted and the absorptive material can more generally eliminate the impact of the energy on the surrounding environment by not just sending it in a different direction but by lowering the overall ambient sound level.
How Do Sound Barriers and Noise Walls Work?
Absorptive surfaces are normally porous and can be effective at high and mid frequencies. Depending on the material used, varying levels of absorption and reduction (Noise Reduction Coefficient) can be achieved. Used in conjunction with a noise blocking material or as part of a composite, the overall result to the environment can be improved. There are also materials that “resonate” at lower frequency that acts as an absorber for the lower octave bands by converting the energy of sound into heat.
Reflective, sound blocking material, such as concrete, steel, and other such heavier “mass” materials, are effective at blocking the energy and redirecting it by reflecting it and changing the path of the sound. These are most typically seen in the Transportation Noise Walls along the highways and in structures that require shielding from external noise. The physical location and dimensions of these barriers are most important and they are often tall and wide to work properly, it is best used in expansive environments.
Sound is an energy wave that requires a medium to travel through for propagation. There is no sound in a vacuum and by changing the density, mass, and compression of the medium ( a de-coupled barrier), the intensity, power, and character of the energy can be changed. Understanding the characteristics of sound is vital to being able to provide correct solutions for each situation.
Commercial soundproofing usually encompasses a combination of sound dampeners, porous and non-porous materials, and flat, reflective sound walls. This is because commercial applications require a variety of sound frequencies to be addressed. In addition to soundproof barriers alongside highways and other roadways, many buildings are constructed with soundproofing materials and designed in a way that cuts down on noise pollution. For example, materials such as concrete sound barriers may be built outside, with several noise absorbing features inside the walls.