Repeatability of the European Standardized Method for Measuring Sound Reflection and Sound Insulation of Noise Barriers

The EN 1793-5 and 1793-6 standards have been in use for many years as a method measuring the intrinsic characteristics of noise barriers installed along highways railways. They require sound source grid microphones, to be placed near barrier free field conditions, according predetermined distances. In principle, small errors positioning microphone may affect results obtained. An international round-robin test was carried out 2012 evaluate repeatability reproducibility method, but until now no studies compare laboratory versus in-place measurements performed with same equipment its variance when an imperfect microphones is taken into account. present work, multiple series reflection index insulation on kind or highway are presented. were repeated different ways: (1) laboratory, leaving unmoved assess measurement system under controlled conditions; (2) repositioning each robustness real conditions environment; (3) situ, open traffic, critical environment. both measurements, standard deviation single-number ratings all cases examined well below value presented 1793-6, which obtained from statistical analysis dozen ago, suggesting that expert operators state-of-the art can achieve much better now.