Handling of Barriers in ISO 9613-2

This paper describes how sound barriers, or sound screens as they are called in ISO 9613-2 are one of the primary tools used in noise control engineering. The ability to accurately estimate the attenuation of a sound barrier is critical to the successful noise control design of many industrial facilities. However, far too often noise control engineers ignore the details buried within the barrier attenuation algorithms and rely on computer methods to handle critical calculations. One of the more popular algorithms for barrier insertion loss is that defined by the ISO 9613-2 standard. The ISO 9613-2 screening attenuation equations and rules are cast as a simple method for determining the effectiveness of a sound barrier in the presence of a ground plane. The method is conducive for computer predictions made on personal computers with limited computational resources. It is often used in spreadsheet analysis or in dedicated environmental sound modeling software. Currently, the algorithm is widely used in environmental noise modeling software. Issues associated with the perceived accuracy of the ISO 9613-2 screening algorithm can be broken down into 3 categories: (1) misinterpretations by ISO 9613-2 users of the formulas/rules that can lead to erroneous results or discontinuity of the results; (2) ISO 9613-2’s omissions in regard to rules for handling special cases; and (3) physical phenomena that ISO 9613-2 does not account for. This paper provides a critical assessment of the adequacy of the ISO 9613-2 barrier attenuation algorithm and identifies many misconceptions of its use and deficiencies of the algorithm.