Application of sound absorption measurements according to EN 1793-5 on gabion walls

The standard EN 1793-5 describes a method to determine the sound reflection index of road traffic noise reducing devices under direct sound field conditions in-situ. The method is commonly used to assess the intrinsic characteristics of conventional, absorptive noise barriers and yields results with a limited measurement uncertainty. Recently, the sound reflection index of a gabion wall was determined by means of the in-situ measurement method leading to unexpected results. An in-depth analysis was made of the results of the in-situ measurements on a conventional noise barrier and on a gabion wall. The main conclusion of this comparison is that application of the in-situ method on a gabion wall has a much higher measurement uncertainty than to be expected.