## Laboratory method for sound absorption (EN 1793-1)

This section contains separate diagrams for each measurement method taken into account. Based on data analyses and proof of consistency, four main categories have been defined in order to have enough statistical relevance for each category. The diagram below shows the distribution of the single number rating according to method for the main identified noise barrier categories. The coloured dotted points represent the values of the single number rating for each category. The grey area represents the so-called violin plot, which shows a kernel density estimation of the probability density of the data.