An acoustic screen or sound wall gets its effectiveness from proper placement between a noise source, such as traffic or neighboring noise, and a receiver, such as yourself in your yard. By placing an obstacle in the direct sound path of noise pollution in the form of a sound wall with certain properties such as mass, absorption and gap density, you obtain a low-noise shadow zone behind the wall. Thanks to this shaded area, for example, you can enjoy a quiet garden.
This principle is also called Maekawa’s Principle, after the Japanese professor who researched and mapped it in detail. Maekawa studied the effect on different frequencies of sound and mapped noise reduction behind a sound wall. For example, he stated that the performance of a sound wall depends on a number of parameters: The distance from the sound source to the wall, the height of the wall and the distance to the receiver behind the wall.
Sound absorbing screens can absorb one-sided or two-sided. These screens also have soundproofing or sound insulating properties, of course, but also absorb some of the sound thanks to their acoustic core. The sound energy that comes in contact with the absorbing surface of the panel disappears to some extent into the acoustic core, and the sound waves die out in that core, so to speak. This occurs according to frequency to a greater or lesser extent depending on the type of screen, thickness and density of the acoustic core used. The degree of absorption is calculated from the Alpha coefficient which gives a measure between 0 and 1 of how much sound energy is absorbed.
Adding an absorbent surface to the sound wall helps reduce high noise levels behind the screen, but also greatly reduces reverberation time or echo. By creating fewer reflections, absorbent panels will therefore also provide solutions in smaller gardens or for noise pollution from machinery such as air conditioners and heat pumps.
